USE flag index

---

Global USE flags

Flag	Description
3dfx	Enable support for Voodoo chipsets, also called as 3DFX and TDFX
X	Add support for X11
Xaw3d	Add support for the 3d athena widget set
a52	Enable support for decoding ATSC A/52 streams used in DVD
aac	Enable support for MPEG-4 AAC Audio
aalib	Add support for media-libs/aalib (ASCII-Graphics Library)
accessibility	Add support for accessibility (eg 'at-spi' library)
acl	Add support for Access Control Lists
acpi	Add support for Advanced Configuration and Power Interface
adns	Add support for asynchronous DNS resolution
afs	Add OpenAFS support (distributed file system)
alsa	Add support for media-libs/alsa-lib (Advanced Linux Sound Architecture)
altivec	Add support for optimizations for G4 and G5/ppc970 processors
ao	Use libao audio output library for sound playback
apache2	Add Apache2 support
apm	Add APM (Advanced Power Management) support
aqua	Include support for the Mac OS X Aqua (Carbon/Cocoa) GUI
atm	Enable Asynchronous Transfer Mode protocol support
audiofile	Add support for libaudiofile where applicable
audit	Enable support for Linux audit subsystem using sys-process/audit
avahi	Add avahi/Zeroconf support
ayatana	Build in support for Ayatana notification using the libindicate or libappindicator plugin
bash-completion	Enable bash-completion support
bcmath	Add support for libbcmath
berkdb	Add support for sys-libs/db (Berkeley DB for MySQL)
bidi	Enable bidirectional language support
big-endian	Big-endian toolchain support
bindist	Flag to enable or disable options for prebuilt (GRP) packages (eg. due to licensing issues)
blas	Add support for the virtual/blas numerical library
bluetooth	Enable Bluetooth Support
bootstrap	!!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used during original system bootstrapping [make stage2]
boundschecking	Add the bounds checking patch by Haj Ten Brugge, this will DISABLE the hardened PIE+SSP patches
branding	Enable Gentoo specific branding
bsf	Enable support for Apache Bean Scripting Framework (dev-java/bsf)
build	!!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used for creating build images and the first half of bootstrapping [make stage1]
bzip2	Use the bzlib compression library
cairo	Enable support for the cairo graphics library
calendar	Add support for calendars (not using mcal!)
canna	Add support for the Canna kana to kanji conversion engine
caps	Use Linux capabilities library to control privilege
cdb	Add support for the CDB database engine from the author of qmail
cdda	Add Compact Disk Digital Audio (Standard Audio CD) support
cddb	Access cddb servers to retrieve and submit information about compact disks
cdinstall	Copy files from the CD rather than asking the user to copy them, mostly used with games
cdparanoia	Enable cdparanoia (audio CD ripper) support
cdr	Add support for CD writer hardware
cgi	Add CGI script support
cjk	Add support for Multi-byte character languages (Chinese, Japanese, Korean)
clamav	Add support for Clam AntiVirus software (usually with a plugin)
connman	Add support for net-misc/connman
coreaudio	Build the CoreAudio driver on Mac OS X systems
cracklib	Support for cracklib strong password checking
crypt	Add support for encryption -- using mcrypt or gpg where applicable
cscope	Enable cscope interface -- in vim for example
css	Enable reading of encrypted DVDs
ctype	Enable ctype functions
cups	Add support for CUPS (Common Unix Printing System)
curl	Add support for client-side URL transfer library
custom-cflags	Build with user-specified CFLAGS (unsupported)
cvs	Enable CVS (Concurrent Versions System) integration
cxx	Build support for C++ (bindings, extra libraries, code generation, ...)
dbi	Enable dev-db/libdbi (database-independent abstraction layer) support
dbm	Add support for generic DBM databases
dbus	Enable dbus support for anything that needs it (gpsd, gnomemeeting, etc)
debug	Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
dedicated	Add support for dedicated game servers (some packages do not provide clients and servers at the same time)
dga	Add DGA (Direct Graphic Access) support for X
directfb	Add support for DirectFB layer (library for FB devices)
djvu	Support DjVu, a PDF-like document format esp. suited for scanned documents
doc	Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
dri	Enable direct rendering: used for accelerated 3D and some 2D, like DMA
dts	Enable DTS Coherent Acoustics decoder support
dv	Enable support for a codec used by many camcorders
dvb	Add support for DVB (Digital Video Broadcasting)
dvd	Add support for DVDs
dvdr	Add support for DVD writer hardware (e.g. in xcdroast)
eds	Enable support for Evolution-Data-Server (EDS)
emacs	Add support for GNU Emacs
emboss	Add support for the European Molecular Biology Open Software Suite
encode	Add support for encoding of audio or video files
enscript	Add enscript support to colourize code stored in the repository
evo	Add support for mail-client/evolution
examples	Install examples, usually source code
exif	Add support for reading EXIF headers from JPEG and TIFF images
expat	Enable the use of dev-libs/expat for XML parsing
fam	Enable FAM (File Alteration Monitor) support
fastcgi	Add support for the FastCGI interface
fbcon	Add framebuffer support for the console, via the kernel
ffmpeg	Enable ffmpeg/libav-based audio/video codec support
fftw	Use FFTW library for computing Fourier transforms
filecaps	Use Linux file capabilities to control privilege rather than set*id (this is orthogonal to USE=caps which uses capabilities at runtime e.g. libcap)
firebird	Add support for the Firebird relational database
flac	Add support for FLAC: Free Lossless Audio Codec
flatfile	Add dbm support for flat files
fltk	Add support for the Fast Light Toolkit gui interface
fontconfig	Support for configuring and customizing font access via media-libs/fontconfig
foomaticdb	Add support for the foomatic printing driver database
fortran	Add support for fortran
freetds	Add support for the TDS protocol to connect to MSSQL/Sybase databases
freewnn	Add support for FreeWnn kana to kanji conversion engine
ftp	Add FTP (File Transfer Protocol) support
gcj	Enable building with gcj (The GNU Compiler for the Javatm Programming Language)
gd	Add support for media-libs/gd (to generate graphics on the fly)
gdbm	Add support for sys-libs/gdbm (GNU database libraries)
geoip	Add geoip support for country and city lookup based on IPs
geolocation	Enable physical position determination
ggi	Add support for media-libs/libggi (non-X video api/drivers)
gif	Add GIF image support
gimp	Build a plugin for the GIMP
git	Enable git (version control system) support
glut	Build an OpenGL plugin using the GLUT library
gmp	Add support for dev-libs/gmp (GNU MP library)
gnome	Add GNOME support
gnome-keyring	Enable support for storing passwords via gnome-keyring
gnuplot	Enable support for gnuplot (data and function plotting)
gnutls	Prefer net-libs/gnutls as SSL/TLS provider (ineffective with USE=-ssl)
gphoto2	Add digital camera support
gpm	Add support for sys-libs/gpm (Console-based mouse driver)
gps	Add support for Global Positioning System
graphicsmagick	Build and link against GraphicsMagick instead of ImageMagick (might require USE=imagemagick if optional)
graphviz	Add support for the Graphviz library
gsl	Use the GNU scientific library for calculations
gsm	Add support for the gsm lossy speech compression codec
gstreamer	Add support for media-libs/gstreamer (Streaming media)
gtk	Add support for x11-libs/gtk+ (The GIMP Toolkit)
gtk-doc	Build and install gtk-doc based developer documentation for dev-util/devhelp, IDE and offline use
guile	Add support for the guile Scheme interpreter
gzip	Compress files with Lempel-Ziv coding (LZ77)
handbook	Enable handbooks generation for packages by KDE
hardened	Activate default security enhancements for toolchain (gcc, glibc, binutils)
hddtemp	Enable monitoring of hdd temperature (app-admin/hddtemp)
hdf5	Add support for the Hierarchical Data Format v5
headers-only	Install only C headers instead of whole package. Mainly used by sys-devel/crossdev for toolchain bootstrap.
hscolour	Include coloured haskell sources to generated documentation (dev-haskell/hscolour)
ibm	Add support for IBM ppc64 specific systems
iconv	Enable support for the iconv character set conversion library
icq	Enable ICQ IM protocol support
icu	Enable ICU (Internationalization Components for Unicode) support, using dev-libs/icu
idn	Enable support for Internationalized Domain Names
ieee1394	Enable FireWire/iLink IEEE1394 support (dv, camera, ...)
imagemagick	Enable optional support for the ImageMagick or GraphicsMagick image converter
imap	Add support for IMAP (Internet Mail Application Protocol)
imlib	Add support for imlib, an image loading and rendering library
infiniband	Enable Infiniband RDMA transport support
inifile	Add dbm support for .ini files
inotify	Enable inotify filesystem monitoring support
introspection	Add support for GObject based introspection
iodbc	Add support for iODBC library
ios	Enable support for Apple's iDevice with iOS operating system (iPad, iPhone, iPod, etc)
ipod	Enable support for iPod device access
ipv6	Add support for IP version 6
iwmmxt	Add support for optimizations for ARM iwMMXt instructions
jack	Add support for the JACK Audio Connection Kit
java	Add support for Java
javascript	Enable javascript support
jbig	Enable jbig-kit support for tiff, Hylafax, ImageMagick, etc
jingle	Enable voice calls for jabber
jit	Enable just-in-time compilation for improved performance. May prevent use of some PaX memory protection features in Gentoo Hardened.
joystick	Add support for joysticks in all packages
jpeg	Add JPEG image support
jpeg2k	Support for JPEG 2000, a wavelet-based image compression format
kde	Add support for KDE (K Desktop Environment)
kerberos	Add kerberos support
ladspa	Enable the ability to support ladspa plugins
lame	Prefer using LAME libraries for MP3 encoding support
lapack	Add support for the virtual/lapack numerical library
lash	Add LASH Audio Session Handler support
latex	Add support for LaTeX (typesetting package)
lcms	Add lcms support (color management engine)
ldap	Add LDAP support (Lightweight Directory Access Protocol)
libass	SRT/SSA/ASS (SubRip / SubStation Alpha) subtitle support
libav	Prefer libav over ffmpeg whenever both are supported
libcaca	Add support for colored ASCII-art graphics
libedit	Use the libedit library (replacement for readline)
libffi	Enable support for Foreign Function Interface library
libnotify	Enable desktop notification support
libressl	Use dev-libs/libressl instead of dev-libs/openssl when applicable (see also the ssl useflag)
libsamplerate	Build with support for converting sample rates using libsamplerate
libwww	Add libwww support (General purpose WEB API)
lirc	Add support for lirc (Linux's Infra-Red Remote Control)
livecd	!!internal use only!! DO NOT SET THIS FLAG YOURSELF!, used during livecd building
lm_sensors	Add linux lm_sensors (hardware sensors) support
lua	Enable Lua scripting support
luajit	Use dev-lang/luajit instead of dev-lang/lua (ineffective with USE=-lua)
lzma	Support for LZMA (de)compression algorithm
lzo	Enable support for lzo compression
m17n-lib	Enable m17n-lib support
mad	Add support for mad (high-quality mp3 decoder library and cli frontend)
maildir	Add support for maildir (~/.maildir) style mail spools
matroska	Add support for the matroska container format (extensions .mkv, .mka and .mks)
mbox	Add support for mbox (/var/spool/mail) style mail spools
memcached	Add support for memcached
memlimit	Add memory usage limiting in supporting programs
mhash	Add support for the mhash library
migemo	Enable migemo support for Japanese
mikmod	Add libmikmod support to allow playing of SoundTracker-style music files
milter	Add sendmail mail filter (milter) support
mime	Add MIME support
minimal	Install a very minimal build (disables, for example, plugins, fonts, most drivers, non-critical features)
mmap	Add mmap (memory map) support
mms	Support for Microsoft Media Server (MMS) streams
mng	Add support for libmng (MNG images)
modplug	Add libmodplug support for playing SoundTracker-style music files
modules	Build the kernel modules
mono	Build Mono bindings to support dotnet type stuff
motif	Add support for the Motif toolkit
mozilla	Add support for the Mozilla web-browser
mp3	Add support for reading mp3 files
mp4	Support for MP4 container format
mpeg	Add libmpeg3 support to various packages
mpi	Add MPI (Message Passing Interface) layer to the apps that support it
mplayer	Enable mplayer support for playback or encoding
msn	Enable MSN Messenger IM protocol support
mssql	Add support for Microsoft SQL Server database
mtp	Enable support for Media Transfer Protocol
mule	Add multi-language support to XEmacs
multilib	On 64bit systems, if you want to be able to compile 32bit and 64bit binaries
musepack	Enable support for the musepack audio codec
musicbrainz	Lookup audio metadata using MusicBrainz community service (musicbrainz.org)
mysql	Add mySQL Database support
mysqli	Add support for the improved mySQL libraries
nas	Add support for network audio sound
ncurses	Add ncurses support (console display library)
neXt	Enable neXt toolkit
neon	Enable optimization support for ARM NEON processors
netboot	Enable network booting
netcdf	Enable NetCDF data format support
networkmanager	Enable net-misc/networkmanager support
nis	Support for NIS/YP services
nls	Add Native Language Support (using gettext - GNU locale utilities)
nntp	Add support for newsgroups (Network News Transfer Protocol)
nocd	Install all files required to run the application without a CD mounted
nptl	Enable support for Native POSIX Threads Library, the new threading module (requires linux-2.6 or better usually)
nsplugin	Build plugin for browsers supporting the Netscape plugin architecture (that is almost any modern browser)
ocaml	Add support/bindings for the Ocaml language
ocamlopt	Enable ocamlopt support (ocaml native code compiler) -- Produces faster programs (Warning: you have to disable/enable it at a global scale)
oci8	Add Oracle 8 Database Support
oci8-instant-client	Use dev-db/oracle-instantclient-basic as Oracle provider instead of requiring a full Oracle server install
odbc	Add ODBC Support (Open DataBase Connectivity)
offensive	Enable potentially offensive items in packages
ofx	Enable support for importing (and exporting) OFX (Open Financial eXchange) data files
ogg	Add support for the Ogg container format (commonly used by Vorbis, Theora and flac)
openal	Add support for the Open Audio Library
openexr	Support for the OpenEXR graphics file format
opengl	Add support for OpenGL (3D graphics)
openmp	Build support for the OpenMP (support parallel computing), requires >=sys-devel/gcc-4.2 built with USE="openmp"
oracle	Enable Oracle Database support
orc	Use dev-lang/orc for just-in-time optimization of array operations
osc	Enable support for Open Sound Control
oscar	Enable Oscar (AIM/ICQ) IM protocol support
oss	Add support for OSS (Open Sound System)
pam	Add support for PAM (Pluggable Authentication Modules) - DANGEROUS to arbitrarily flip
pch	Enable precompiled header support for faster compilation at the expense of disk space and memory (>=sys-devel/gcc-3.4 only)
pcmcia	Add support for PCMCIA slots/devices found on laptop computers
pcntl	Add support for process creation functions
pcre	Add support for Perl Compatible Regular Expressions
pda	Add support for portable devices
pdf	Add general support for PDF (Portable Document Format), this replaces the pdflib and cpdflib flags
perl	Add optional support/bindings for the Perl language
php	Include support for the PHP language
pie	Build programs as Position Independent Executables (a security hardening technique)
plasma	Build optional KDE plasma addons
plotutils	Add support for plotutils (library for 2-D vector graphics)
png	Add support for libpng (PNG images)
policykit	Enable PolicyKit authentication support
portaudio	Add support for the crossplatform portaudio audio API
posix	Add support for POSIX-compatible functions
postgres	Add support for the postgresql database
postscript	Enable support for the PostScript language (often with ghostscript-gpl or libspectre)
ppds	Add support for automatically generated ppd (printing driver) files
prefix	Defines if a Gentoo Prefix offset installation is used
prelude	Add support/bindings for the Prelude Intrusion Detection System
profile	Add support for software performance analysis (will likely vary from ebuild to ebuild)
pulseaudio	Add support for PulseAudio sound server
python	Add optional support/bindings for the Python language
qdbm	Add support for the qdbm (Quick Database Manager) library
qmail-spp	Add support for qmail SMTP plugins
qt4	Add support for the Qt GUI/Application Toolkit version 4.x
qt5	Add support for the Qt 5 application and UI framework
quicktime	Add support for OpenQuickTime
radius	Add support for RADIUS authentication
raw	Add support for raw image formats
rdp	Enables RDP/Remote Desktop support
readline	Enable support for libreadline, a GNU line-editing library that almost everyone wants
recode	Enable support for the GNU recode library
rss	Enable support for RSS feeds
ruby	Add support/bindings for the Ruby language
samba	Add support for SAMBA (Windows File and Printer sharing)
sasl	Add support for the Simple Authentication and Security Layer
savedconfig	Use this to restore your config from /etc/portage/savedconfig ${CATEGORY}/${PN}. Make sure your USE flags allow for appropriate dependencies
scanner	Add support for scanner hardware (e.g. build the sane frontend in kdegraphics)
sctp	Support for Stream Control Transmission Protocol
sdl	Add support for Simple Direct Layer (media library)
seamonkey	Add support for the Seamonkey web-browser
seccomp	Enable seccomp (secure computing mode) to perform system call filtering at runtime to increase security of programs
selinux	!!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
semantic-desktop	Cross-KDE support for semantic search and information retrieval
session	Add persistent session support
sharedmem	Add support for shared memory use
shorten	Add support for the shorten audio compressor
simplexml	Support for SimpleXML
skey	Enable S/Key (Single use password) authentication support
slang	Add support for the slang text display library (it's like ncurses, but different)
slp	Add Service Locator Protocol support
smartcard	Enable smartcard support
smp	Enable support for multiprocessors or multicore systems
sndfile	Add support for libsndfile
snmp	Add support for the Simple Network Management Protocol if available
soap	Add support for SOAP (Simple Object Access Protocol)
sockets	Add support for tcp/ip sockets
socks5	Add support for the socks5 proxy
sound	Enable sound support
source	Zip the sources and install them
sox	Add support for Sound eXchange (SoX)
speex	Add support for the speex audio codec (used for speech)
spell	Add dictionary support
sqlite	Add support for sqlite - embedded sql database
ssl	Add support for SSL/TLS connections (Secure Socket Layer / Transport Layer Security)
startup-notification	Enable application startup event feedback mechanism
static	!!do not set this during bootstrap!! Causes binaries to be statically linked instead of dynamically
static-libs	Build static versions of dynamic libraries as well
subversion	Enable subversion (version control system) support
suid	Enable setuid root program, with potential security risks
svg	Add support for SVG (Scalable Vector Graphics)
svga	Add support for SVGAlib (graphics library)
sybase	Add support for the Sybase SQL Database Server
sybase-ct	Add support for Sybase-CT
symlink	Force kernel ebuilds to automatically update the /usr/src/linux symlink
syslog	Enable support for syslog
systemd	Enable use of systemd-specific libraries and features like socket activation or session tracking
sysvipc	Support for System V-compatible inter-process communication
szip	Use the szip compression library
taglib	Enable tagging support with taglib
tcl	Add support the Tcl language
tcmalloc	Use the dev-util/google-perftools libraries to replace the malloc() implementation with a possibly faster one
tcpd	Add support for TCP wrappers
test	Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)
theora	Add support for the Theora Video Compression Codec
threads	Add threads support for various packages. Usually pthreads
tidy	Add support for HTML Tidy
tiff	Add support for the TIFF image format
timidity	Build with Timidity++ (MIDI sequencer) support
tk	Add support for Tk GUI toolkit
tokenizer	Add support for the PHP file parser
truetype	Add support for FreeType and/or FreeType2 fonts
uclibc	Enable uclibc specific patches and build or link uclibc
udev	Enable virtual/udev integration (device discovery, power and storage device support, etc)
udisks	Enable storage management support (automounting, volume monitoring, etc)
unicode	Add support for Unicode
unwind	Add support for call stack unwinding and function name resolution
upnp	Enable UPnP port mapping support
upnp-av	Enable UPnP audio/video streaming support
upower	Enable power management support
usb	Add USB support to applications that have optional USB support (e.g. cups)
v4l	Enable support for video4linux (using linux-headers or userspace libv4l libraries)
vaapi	Enable Video Acceleration API for hardware decoding
vala	Enable bindings for dev-lang/vala
vanilla	Do not add extra patches which change default behaviour; DO NOT USE THIS ON A GLOBAL SCALE as the severity of the meaning changes drastically
vcd	Video CD support
vdpau	Enable the Video Decode and Presentation API for Unix acceleration interface
vhosts	Add support for installing web-based applications into a virtual-hosting environment
videos	Install optional video files (used in some games)
vim-syntax	Pulls in related vim syntax scripts
vnc	Enable VNC (remote desktop viewer) support
vorbis	Add support for the OggVorbis audio codec
wavpack	Add support for wavpack audio compression tools
wayland	Enable dev-libs/wayland backend
wddx	Add support for Web Distributed Data eXchange
webkit	Add support for the WebKit HTML rendering/layout engine
webp	Add support for the WebP image format
wifi	Enable wireless network functions
wmf	Add support for the Windows Metafile vector image format
wxwidgets	Add support for wxWidgets/wxGTK GUI toolkit
x264	Enable h264 encoding using x264
xattr	Add support for extended attributes (filesystem-stored metadata)
xcb	Support the X C-language Binding, a replacement for Xlib
xcomposite	Enable support for the Xorg composite extension
xemacs	Add support for XEmacs
xface	Add xface support used to allow a small image of xface format to be included in an email via the header 'X-Face'
xft	Build with support for XFT font renderer (x11-libs/libXft)
xine	Add support for the XINE movie libraries
xinerama	Add support for querying multi-monitor screen geometry through the Xinerama API
xinetd	Add support for the xinetd super-server
xml	Add support for XML files
xmlrpc	Support for xml-rpc library
xmp	Enable support for Extensible Metadata Platform (Adobe XMP)
xmpp	Enable support for Extensible Messaging and Presence Protocol (XMPP) formerly known as Jabber
xosd	Sends display using the X On Screen Display library
xpm	Add support for XPM graphics format
xscreensaver	Add support for XScreenSaver extension
xv	Add in optional support for the Xvideo extension (an X API for video playback)
xvid	Add support for xvid.org's open-source mpeg-4 codec
yahoo	Enable Yahoo Messenger IM protocol support
yaz	Add in optional support for the Z39.50 Protocol for Information Retrieval (YAZ)
zeroconf	Support for DNS Service Discovery (DNS-SD)
zlib	Add support for zlib (de)compression
zsh-completion	Enable zsh completion support

Local USE flags

app-accessibility

brltty

api	build brltty's application program interface
beeper	support the console tone generator
contracted-braille	support in-line contracted braille
fm	support for the sound card synthesizer
midi	support the musical instrument digital interface
pcm	support for sound card digital audio
speech	speech support

eflite

16k_voice	Use a higher-quality voice.

emacspeak

espeak	Adds support for the espeak tts engine

festival-it

mbrola	Adds support for mbrola voices

freetts

jsapi	build Java Speech API (JSAPI)
mbrola	Adds support for mbrola voices

orca

braille	Enable braille support

simon

opencv	Use media-libs/opencv
pim	Enable support for KDE PIM resources integration
sphinx	Build sphinx backend (pulls app-accessibility/julius if disabled

speech-dispatcher

espeak	Adds support for espeak speech engine
flite	Adds support for flite speech engine

speechd-el

brltty	brltty support

app-admin

bcfg2

cheetah	Include dev-python/cheetah support
genshi	Include dev-python/genshi support
server	Installs scripts to be used on the server-side of this app

calamares

pythonqt	Enable PythonQt-based module interface

clsync

cgroups	Use cgroups to limit /dev access.
cluster	Enable clustering support (allows master-master clsync on multiple hosts). Not fully implemented yet.
control-socket	Enable AF_UNIX control socket support.
extra-debug	Enable extra debugging. This will hurt performance badly. Be ready for tons of output.
extra-hardened	Enable extra security checks. This will hurt performance.
gio	Enable GIO for FS monitoring (glib based alternative to inotify interface, not recommended; if both are compiled, may be selected at runtime).
highload-locks	Allows to use spinlocks for short delays instead of mutexes, but only on SMP systems.
namespaces	Enable namespaces isolation.

conky

apcupsd	Enable support for sys-power/apcupsd
audacious	Enable monitoring of music played by media-sound/audacious
cmus	Enable monitoring of music played by media-sound/cmus
eve	Enable support for the eve-online skill monitor
ical	Enable support for events from iCalendar (RFC 5545) files using dev-libs/libical
iostats	Enable support for per-task I/O statistics
irc	Enable support for displaying everything from an irc channel using net-libs/libircclient
lua-cairo	Enable if you want Lua Cairo bindings
lua-imlib	Enable if you want Lua Imlib2 bindings
lua-rsvg	Enable if you want Lua RSVG bindings
math	Enable support for glibc's libm math library
moc	Enable monitoring of music played by media-sound/moc
mpd	Enable monitoring of music controlled by media-sound/mpd
nano-syntax	Enable syntax highlighting for app-editors/nano
nvidia	Enable reading of nvidia card temperature sensors via media-video/nvidia-settings
portmon	Enable support for tcp (ip4) port monitoring
thinkpad	Enable support for IBM/Lenovo notebooks
weather-metar	Enable support for metar weather service
weather-xoap	Enable support for metar and xoap weather service
webserver	Enable support to act as a webserver serving conkys output using net-libs/libmicrohttpd
xmms2	Enable monitoring of music played by media-sound/xmms2

diamond

mongo	Enable MongoDB support
redis	Enable Redis support

diradm

automount	Support for automount data in LDAP
irixpasswd	Support for storing separate IRIX passwords

elektra

augeas	Enable plugin for reading and writing configuration files with help from Augeas
ini	Enable new, advanced ini support
simpleini	Enable simpleini support
uname	Enable uname information for the key database
yajl	Enable yajl support

gkrellm

X	Build both the X11 gui (gkrellm) and the server (gkrellmd). Disabling this flag builds the server only
gnutls	Enable SSL support for mail checking with net-libs/gnutls (overrides 'ssl' USE flag)
hddtemp	Enable monitoring harddrive temperatures via app-admin/hddtemp
lm_sensors	Enable monitoring sensors via sys-apps/lm_sensors
ntlm	Enable NTLM authentication for mail checking with net-libs/libntlm
ssl	Enable SSL support for mail checking with dev-libs/openssl

glance

swift	Adds swift storage support

gtkdiskfree

gtk2	Support GTK+ 2.x instead of GTK+ 3.x

hddtemp

network-cron	Monthly cronjob to update hddtemp.db.

keepass

aot	Generate native code at build time, rather than runtime.

keepassxc

autotype	Add support to autotype the passwords into other applications
browser	Enables browser plugin support
http	Add http support
network	Enable network support
yubikey	Enable database unlocking via YubiKey.

lastpass-cli

X	Use x11-misc/xclip or x11-misc/xsel to copy passwords to the clipboard.
pinentry	Use app-crypt/pinentry to prompt for passwords.

logrotate

acl	Installs acl support
cron	Installs cron file
selinux	Installs Security Enhanced Linux support

logstash-bin

x-pack	Enable additional features (may need a license)

matter

entropy	Add Entropy support

mcollective

client	Install client utilities

mms-agent

monitoring	Install the monitoring agent

openrc-settingsd

systemd	Use the versions of dbus and polkit files provided by sys-apps/systemd

packagekit-base

command-not-found	Enable packagekit support on shell "command not found"
cron	Install cron script for auto-update
elogind	Enable elogind support to get user session
entropy	Enable Entropy backend

pass

X	Use x11-misc/xclip to copy passwords to the clipboard.
dmenu	Add support for x11-misc/dmenu with the 'passmenu' program.
fish-completion	Enable fish completion support.
git	Use dev-vcs/git for password revisions.
importers	Allow importing passwords from other password managers using various contributed scripts.

pass-otp

qrcode	Add support for qrcodes using media-gfx/qrencode

passwordsafe

minimal	Avoid collision with app-misc/pwsafe
qr	Enable QR code password display
xml	Enable XML import support
yubikey	Enable support for Yubikey

prelude-manager

dbx	Enables Prelude Manager storing Prelude alerts into database through dev-libs/libpreludedb .
tcpwrapper	Enables Prelude Manager using tcp wrapper. It requires sys-apps/tcp-wrappers .

puppet

augeas	Enable augeas support
diff	Enable diff support
experimental	Add patches for things in testing
rrdtool	Enable rrdtool support
shadow	Enable shadow support

puppet-agent

experimental	Add patches for things in testing
puppetdb	Adds puppetdb support

puppetserver

puppetdb	Adds support for connecting to puppetdb

pwgen

livecd	Install init script for root password scrambling on boot

pwman3

mongodb	Add support for MongoDB

rsyslog

curl	Enable http_request() function in RainerScript (requires net-misc/curl)
dbi	Build the general database output module (requires dev-db/libdbi)
elasticsearch	Build the Elasticsearch output module (requires net-misc/curl)
gcrypt	Add support for encrypted log files using dev-libs/libgcrypt
gnutls	Build the GnuTLS network stream driver (requires net-libs/gnutls)
grok	Build the grok modify module (requires dev-libs/grok)
jemalloc	Use dev-libs/jemalloc for allocations.
kafka	Build the Apache Kafka input/output module (requires dev-libs/librdkafka)
kerberos	Build the GSSAPI input and output module (requires virtual/krb5)
kubernetes	Build the kubernetes modify plugin (requires net-misc/curl)
libressl	Use dev-libs/libressl instead of dev-libs/openssl (you still need to enable functionality which requires OpenSSL)
mdblookup	Build the MaxMind DB lookup message modify plugin using dev-libs/libmaxminddb
mongodb	Build the MongoDB output module (requires dev-libs/libmongo-client)
mysql	Build the MySQL database output module (requires virtual/mysql)
normalize	Build the normalize modify module (requires dev-libs/libee and dev-libs/liblognorm)
omhttp	Build the http output module (requires net-misc/curl)
omhttpfs	Build the httpfs output module (requires net-misc/curl)
omudpspoof	Build the udpspoof output module (requires net-libs/libnet)
openssl	Build the OpenSSL network stream driver (requires dev-libs/openssl)
postgres	Build the PostgreSQL database output module (requires dev-db/postgresql)
rabbitmq	Build the RabbitMQ output module (requires net-libs/rabbitmq-c)
redis	Build the Redis output module using (requires dev-libs/hiredis)
relp	Build the Reliable Event Logging Protocol (RELP) output module (requires dev-libs/librelp)
rfc3195	Build the rfc3195 input module (requires dev-libs/liblogging)
rfc5424hmac	Build the rfc5424hmac modify module (requires dev-libs/openssl or dev-libs/libressl)
snmp	Build the snmp modify and output module (requires net-analyzer/net-snmp)
ssl	Add support for encrypted client/server communication (requires net-libs/gnutls)
systemd	Build the journal input and output module (requires sys-apps/systemd)
usertools	Installs the user tools (rsgtutil, rscryutil...) corresponding to the set USE flags
uuid	Include UUIDs in messages (requires sys-apps/util-linux)
xxhash	Enable xxHash support in fmhash module (requires dev-libs/xxhash)
zeromq	Build the ZeroMQ input and output modules (requires net-libs/czmq)

sagan

libdnet	Add support for dev-libs/libdnet
lognorm	Add support for log/rules normalizations via dev-libs/liblognorm
pcap	Add support for network packet capture via net-libs/libpcap
smtp	Build witch SMTP (E-Mail) support
snort	Add support to interact with Snort IDE using net-analyzer/snortsam'

sagan-rules

lognorm	Install normalize rules support with dev-libs/liblognorm

salt

cherrypy	Enable support for using cherrypy.
gnupg	Enable support for gnupg via python-gnupg.
keyring	Enable support for keyrings via python-keyring.
libcloud	Enable salt-cloud support via libcloud.
libvirt	Support managing virtual machines with app-emulation/libvirt.
mako	Add support for using the mako template engine for parsing salt states.
mongodb	Support returning data to a mongodb server.
neutron	Support the OpenStack neutron network service.
nova	Enable support for the OpenStack Nova API
openssl	Add support for using TLS via OpenSSL.
portage	Add support for package state enforcement using sys-apps/portage
raet	Add support for the new RAET transport.
redis	Support returning data to a redis database.
timelib	Use timelib to parse english textual date descriptions.
zeromq	Add support for the zeromq transport.

sudo

gcrypt	Use SHA2 from dev-libs/libgcrypt instead of sudo's internal SHA2
offensive	Let sudo print insults when the user types the wrong password
openssl	Use SHA2 from dev-libs/openssl instead of sudo's internal SHA2
sendmail	Allow sudo to send emails with sendmail

sysklogd

logrotate	use app-admin/logrotate for rotating logs rather than custom cron scripts

syslog-ng

amqp	Enable support for AMQP destinations
geoip2	Add support for geo lookup based on IPs via dev-libs/libmaxminddb
http	Enable support for HTTP destinations
json	Enable support for JSON template formatting via dev-libs/json-c
mongodb	Enable support for mongodb destinations
pacct	Enable support for reading Process Accounting files (EXPERIMENTAL, Linux only)
redis	Enable support for Redis destinations
smtp	Enable support for SMTP destinations
spoof-source	Enable support for spoofed source addresses

sysstat

isag	Install isag, the Interactive System Activity Graph tool

systemrescuecd-x86

isohybrid	Pass downloaded images through isohybrid in order to make it possible to copy them directly to USB media and boot (requires sys-boot/syslinux at build time).

testdisk

ewf	Include ewf library
ntfs	Include the ability to read NTFS filesystems
reiserfs	Include reiserfs reading ability

tripwire

ssl	Adds support for Secure Socket Layer connections
static	Builds the package statically
tools	Installs app-admin/mktwpol, providing scripts for the installation/setup of tripwire, including generating the tripwire policy file and maintenance of the tripwire database

ulogd

json	Build JSON output plugin to save packets in JSON file format
nfacct	Build NFACCT input plugin to support traffic accounting via nfnetlink_acct
nfct	Build NFCT input plugin to support stateful flow-based logging via nfnetlink_conntrack
nflog	Build NFLOG input plugin to support stateless packet-based logging via nfnetlink_log
pcap	Build PCAP output plugin to save packets in libpcap file format
ulog	Build ULOG input plugin to support deprecated packet-based logging via ULOG target

webalizer

xtended	Include the 404 extension

webapp-config

portage	Propagete python_targets dependencies to sys-apps/portage

yaala

storable	Support for persistence of Perl data structures.

app-antivirus

clamav

clamdtop	A Top like tool which shows what clamd is currently scanning amongst other things
metadata-analysis-api	Enables collection of file property metadata using ClamAV API for analysis by ClamAV bytecode programs.
system-libmspack	Use system libmspack instead of built in

clamtk

kde	Install the Dolphin plugin.
nautilus	Install the Nautilus plugin.
nemo	Install the Nemo plugin.
thunar	Install the Thunar plugin.

app-arch

cabextract

extras	Install experimental extra tools: wince_info and wince_rename for examining and processing Windows CE installation cabinet header files; cabinfo for examining the structure of a cab file.

cfv

bittorrent	Enable support for checking .torrent files

deltarpm

system-zlib	Use system sys-libs/zlib. Do not enable features of rsync friendly.

dpkg

update-alternatives	Install update-alternatives

dump

ermt	encrypted rmt support
uuid	Enable UUID support

engrampa

caja	Enable engrampa to integrate with mate-base/caja by providing entries in its context menu
gtk3	Build with GTK+3 instead of GTK+2
magic	Enable filetype auto-detection via sys-apps/file
packagekit	Enable support for installing via app-admin/packagekit based on archive type

file-roller

nautilus	Build contextual menu extension for gnome-base/nautilus.
packagekit	Enable support for the distro-neutral package manager GUI app-admin/packagekit

gzip

pic	disable optimized assembly code that is not PIC friendly

innoextract

debug	Enable debug logging and the --debug command-line option
lzma	Enable support for extracting lzma-compressed installers using app-arch/xz-utils

libarchive

bzip2	Allow accessing bzip2-compressed archives through libbz2 (which comes with app-arch/bzip2). This only affects libarchive's native support: bsdtar will keep using bunzip2 as a filter if that's not built-in.
e2fsprogs	Use file flags from sys-fs/e2fsprogs headers instead of virtual/os-headers headers
lz4	Enable support for LZ4 compression using app-arch/lz4
nettle	Use dev-libs/nettle as crypto backend
zlib	Allow accessing gzip-compressed archives through sys-libs/zlib. This only affects libarchive's native support: bsdtar will keep using gunzip as a filter if that's not built-in. It's also needed for supporting extraction of ZIP files.

p7zip

rar	Enable support for non-free rar decoder

pbzip2

symlink	Install symlinks which override app-arch/bzip2 implementation

pigz

symlink	Install symlinks which override app-arch/gzip implementation

rar

all_sfx	Install all SFX (Self-Extracting) files rather than just the native format (allows creation of Windows EXEs on Linux ELF systems)

rpm

zstd	Enable support for ZSTD compression using app-arch/zstd

tar

minimal	just install `tar`

unzip

natspec	Use dev-libs/libnatspec to correctly decode non-ascii file names archived in Windows.

wimlib

fuse	Use fuse libraries
iso	Install app-cdr/cdrtools in order to prepare iso images
ntfs	Use libntfs-3g library from sys-fs/ntfs3g
openssl	Use the SHA-1 message digest from libcrypto instead of compilling another implementation
yasm	Use yasm assembler instead of nasm

xz-utils

extra-filters	Build additional filters that are not used in any of the default xz presets. This includes delta and BCJ coders, additional match finders and SHA256 checks.

zip

natspec	Use dev-libs/libnatspec to correctly decode non-ascii file names archived in Windows.

zstd

lz4	Enable support for LZ4 compression using app-arch/lz4

app-backup

amanda

ndmp	Support for the NDMP protocol
s3	Support for backing up to the Amazon S3 system
xfs	Support for backing up raw XFS filesystems using xfsdump

backup-manager

s3	Support for backing up to the Amazon S3 system

bacula

bacula-clientonly	Disable DB support, and just build a client
bacula-nodir	Disable building of director
bacula-nosd	Disable building of storage daemon
logwatch	Install support files for logwatch

bareos

cephfs	Enable cephfs storage backend
clientonly	Only install file-daemon (client)
director	Install director
fastlz	Enable support vor lz4, lz4hc and lzfast using dev-libs/bareos-fastlzlib
glusterfs	Enable glusterfs storage backend
gnutls	When ssl is enabled, use GnuTLS instead of OpenSSL
jansson	JSON API support using JANSSON for director
lmdb	enable build of LMDB support for faster accurate backup
logwatch	Install support files for logwatch
ndmp	Enable support for NDMP (Network Data Management Protocol)
rados	Enable rados storage backend
rados-striper	Enable use of rados-striper
scsi-crypto	Enable low level SCSI crypto support
sql-pooling	Enable SQL pooling support
storage-daemon	Install storage daemon (bareos-sd)

btrbk

pv	Use sys-apps/pv to enable progress bar functionality

bup

web	Support browsing backups via a web interface

dar

dar32	Enables --enable-mode=32 option, which replace infinite by 32 bit integers
dar64	Enables --enable-mode=64 option, which replace infinite by 64 bit integers
gcrypt	Enables strong encryption support
gpg	Enables usage of asymetric crypto algorithms

deja-dup

nautilus	Build gnome-base/nautilus extension

duplicity

s3	Support for backing up to the Amazon S3 system

fsarchiver

lz4	Enable lz4 compression support
zstd	Enable zstd compression support

rear

udev	Have ReaR start backup when attaching your USB drive.

snapper

btrfs	Include Btrfs support sys-fs/btrfs-progs
ext4	Include Ext4 support sys-fs/e2fsprogs
lvm	Enable LVM thinprovisioned snapshots support sys-fs/lvm2
xattr	Add support for getting and setting POSIX extended attributes, through sys-apps/attr.

tsm

tsm_cit	IBM Tivoli Common Inventory Technology
tsm_hw	Difference snapshot support for NetApp and N-Series file servers

zbackup

tartool	Install tartool utility

app-benchmarks

filebench

auto-completion	Enable command-line autocompletion using dev-libs/libtecla

httperf

idleconn	Build with the idleconn program

ramspeed

pic	Force shared libraries to be built as PIC (this is slower)

sysbench

aio	Enable libaio support

app-cdr

brasero

libburn	Enable dev-libs/libburn backend
nautilus	Build the gnome-base/nautilus extension
packagekit	Enable support for the distro-neutral package manager GUI app-admin/packagekit
playlist	Enable support for playlists through dev-libs/totem-pl-parser
tracker	Enable audio playlist search using the app-misc/tracker indexer

cdemu

cdemu-daemon	Pull app-cdr/cdemu-daemon dependency, useful in chroot environment (bug #315491). Do not disable until you know what you are doing.

dvdisaster

debug	Enable memory debugging.

gaffitter

scripts	Install additional gaffitter scripts for external programs

mirage2iso

pinentry	Support app-crypt/pinentry password input backend.

app-crypt

aespipe

asm	Enable assembly modules
cpu_flags_x86_padlock	Use VIA padlock instructions, detected at run time, code still works on non-padlock processors

ccid

kobil-midentity	Build and install Kobil_mIDentity_switch tool
twinserial	Enable twinserial reader

codecrypt

cryptopp	Build algorithms that need Crypto++ support dev-libs/crypto++

dehydrated

cron	Install cron job to sign/renew non-existent/changed/expiring certificates

eid-mw

dialogs	Enable "askaccess" dialog box, by using x11-libs/gtk+
gtk	All dialogs are available, by using x11-libs/gtk+
p11-kit	Support for app-crypt/p11-kit.
xpi	Build and install an extension for Mozilla browsers.

ekeyd

minimal	Only install the ekey-egd-linux service rather than the full ekeyd package.
munin	Install a plugin for net-analyzer/munin to graph statistical data from ekeyd.
usb	Build the libusb-based userland daemon for accessing the EntropyKey (alternative to the CDC USB driver). It is suggested to use this option by default, as the CDC driver in the kernel often seems to be fragile (or the gadget implementation on the EntropyKey is too buggy), and can cause various problems.

gnupg

mta	Build mta support using virtual/mta.
smartcard	Build scdaemon software. Enables usage of OpenPGP cards. For other type of smartcards, try app-crypt/gnupg-pkcs11-scd. Bring in dev-libs/libusb as a dependency; enable scdaemon.
tofu	Enable support for Trust on First use trust model; requires dev-db/sqlite.
tools	Install extra tools (including gpgsplit and gpg-zip).
usb	Build direct CCID access for scdaemon; requires dev-libs/libusb.
wks-server	Install the wks-server

gnupg-pkcs11-scd

proxy	Build the gnupg-pkcs11-scd-prox

gpgme

common-lisp	Install common-lisp files

heimdal

hdb-ldap	Adds support for LDAP as a database backend
otp	Adds support for one-time passwords
pkinit	Adds support for PKINIT for the initial ticket

hmaccalc

fips	Enable NSS FIPS mode and support only the FIPS-compliant functions

johntheripper

cuda	Use nvidia cuda toolkit for speeding up cracking on capable devices
mozilla	Support mozilla password cracking
opencl	Enable opencl support for speeding up cracking on capable devices

kbfs

git	Build the Git remote helper for storing repositories in Keybase

kstart

afs	Enables afs support which means you can acquire an afs token and set PAGs. It's recommended to set this USE if you need authenticated access to an AFS cell for your daemon/app.

libb2

native-cflags	Use CFLAGS as determined by configure script. These flags will enable all CPU specific features it find available, to further optimise the implementation. This discards any existing CFLAGS set in make.conf or similar.

libu2f-host

systemd	Use user ACLs rather than plugdev group to give user access to the HIDRAW device.

mit-krb5

doc	Creates and installs the API and implementation documentation. This is only useful if you want to develop software which depends on kerberos.
keyutils	Enable for the keyring ccache using keyutils.
openldap	Enable support for ldap as a database backend.
pkinit	Enable pkinit support for the initial ticket.

ophcrack

tables	Require the additional tables used to carry out cracking (app-crypt/ophcrack-tables)

ophcrack-tables

vistafree	Installs the free Vista ophcrack tables
xpfast	Installs the fast XP ophcrack tables
xpsmall	Installs the small free XP ophcrack tables

p11-kit

asn1	Enable ASN.1 certificate support
trust	Build the trust policy module

qca

botan	Enable botan plugin
gcrypt	Enable gcrypt plugin
gpg	Enable GnuPG plugin
logger	Enable logger plugin
nss	Enable NSS plugin
pkcs11	Enable PKCS#11 plugin
sasl	Enable SASL plugin
softstore	Enable softstore plugin

seahorse

ldap	Enable seahorse to manipulate GPG keys on a LDAP server.

tpm-emulator

mtm-emulator	Build the MTM emulator

tpm-tools

pkcs11	Build Token data management utilities based on OpenCryptoki's (dev-libs/opencryptoki) PKCS#11 implementation.

veracrypt

asm	Enable assembly for optimization

zulucrypt

gnome	Enable support for the freedesktop.org Secret Service API via app-crypt/libsecret
kwallet	Enable encrypted storage of passwords with kde-frameworks/kwallet
udev	Whether udev will be consulted when deciding if a volume is system or not

app-dicts

aspell-be

classic	Support classic spelling by default

gwaei

hunspell	Enable app-text/hunspell spellchecking and morphological analysis
mecab	Enable app-text/mecab support

myspell-pt

preao	Use the pre ortographic agreement version of the dictionary

app-doc

clsync-docs

api	Install doxygen generated API docs.

csound-manual

html	Install HTML documentation

doxygen

clang	support for sys-devel/clang assisted parsing
dot	allow to create dot graphs using media-gfx/graphviz
doxysearch	build doxyindexer and doxysearch.cgi

gnucash-docs

l10n_C	English

kicad-doc

html	Generate documentation in HTML format
pdf	Generate documentation in PDF format

linuxfromscratch

htmlsingle	Install all-on-one-page HTML version.

pms

binary	Download pre-built files instead of building from sources
html	Generate PMS as .html as well
twoside	Enable two-sided layout suitable for printing

tldp-howto

html	Install multi-chapter HTML docs
htmlsingle	Install all-on-one-page HTML docs
pdf	Install pdf docs
text	Install plain-text docs

app-editors

bluefish

gtk2	Enable GTK2 instead of GTK3 even if GTK3 is available
gtk3	Enable GTK3 interface (default)
gucharmap	Enable gucharmap dictionary plugin
python	Enable Python integration for zen-coding plugin
spell	Enable spell checking capabilities via enchant library

emacs

athena	Enable the MIT Athena widget set (x11-libs/libXaw)
dynamic-loading	Enable loading of dynamic libraries at runtime
games	Support shared score files for games
gconf	Use gnome-base/gconf to read the system font name
gfile	Use gfile (dev-libs/glib) for file notification
gsettings	Use gsettings (dev-libs/glib) to read the system font name
gtk2	Prefer version 2 of the GIMP Toolkit to version 3 (x11-libs/gtk+)
gtk3	Prefer version 3 of the GIMP Toolkit to version 2 (x11-libs/gtk+)
gzip-el	Compress bundled Emacs Lisp source
imagemagick	Use media-gfx/imagemagick for image processing
libxml2	Use dev-libs/libxml2 to parse XML instead of the internal Lisp implementations
mailutils	Retrieve e-mail using net-mail/mailutils instead of the internal movemail substitute
source	Install C source files and make them available for find-function
toolkit-scroll-bars	Use the selected toolkit's scrollbars in preference to Emacs' own scrollbars
wide-int	Prefer wide Emacs integers (typically 62-bit). This option has an effect only on architectures where "long" and "long long" types have different size.
xwidgets	Enable use of GTK widgets in Emacs buffers (requires GTK3)

emacs-vcs

athena	Enable the MIT Athena widget set (x11-libs/libXaw)
dynamic-loading	Enable loading of dynamic libraries at runtime
games	Support shared score files for games
gconf	Use gnome-base/gconf to read the system font name
gfile	Use gfile (dev-libs/glib) for file notification
gsettings	Use gsettings (dev-libs/glib) to read the system font name
gtk2	Prefer version 2 of the GIMP Toolkit to version 3 (x11-libs/gtk+)
gzip-el	Compress bundled Emacs Lisp source
imagemagick	Use media-gfx/imagemagick for image processing
json	Compile with native JSON support using dev-libs/jansson
libxml2	Use dev-libs/libxml2 to parse XML instead of the internal Lisp implementations
mailutils	Retrieve e-mail using net-mail/mailutils instead of the internal movemail substitute
source	Install C source files and make them available for find-function
threads	Add elisp threading support
toolkit-scroll-bars	Use the selected toolkit's scrollbars in preference to Emacs' own scrollbars
wide-int	Prefer wide Emacs integers (typically 62-bit). This option has an effect only on architectures where "long" and "long long" types have different size.
xwidgets	Enable use of GTK widgets in Emacs buffers (requires GTK3)

fe

sendmail	Send mail after editor abend

gedit-plugins

charmap	Insert special characters just by clicking on them
git	Shows document changes related to git's HEAD
terminal	Embed a terminal in the bottom pane

gvim

gtk3	Enable GTK+3 interface
netbeans	Include netbeans external editor integration support
racket	Enable support for Scheme using dev-scheme/racket

jasspa-microemacs

nanoemacs	Build NanoEmacs instead of MicroEmacs

joe

xterm	Enable full xterm clipboard support

latexila

latexmk	Install dev-tex/latexmk (used by default for the build tools)
rubber	Install dev-tex/rubber (can be used for the build tools)

leafpad

emacs	Enable Emacs key theme

mousepad

gtk3	Use GTK+3 instead of GTK+2

nano

debug	Enable debug messages and assert warnings. Note that these will all be sent straight to stderr rather than some logging facility.
justify	Enable justify/unjustify functions for text formatting.
magic	Add magic file support (sys-apps/file) to automatically detect appropriate syntax highlighting
minimal	Disable all fancy features, including ones that otherwise have a dedicated USE flag (such as spelling).

ne

tinfo	Link against libtinfo from sys-libs/ncurses

neovim

clipboard	Enable clipboard support through a provider
jemalloc	Use dev-libs/jemalloc for allocations
nvimpager	Install nvimpager symlink to less.sh macro
remote	Enable support for remote options using nvr
tui	Build the neovim unix tui

okteta

designer	Build plugins for dev-qt/designer

pluma

gtk3	Build with GTK+3 instead of GTK+2

qhexedit2

gui	Install Qt5 hex editor

tea

aspell	Enable spellchecking using app-text/aspell
hunspell	Enable spellchecking using app-text/hunspell
qml	Enable support for plugins using QML

vim

X	Link console vim against X11 libraries to enable title and clipboard features in xterm
racket	Enable support for Scheme using dev-scheme/racket
terminal	Enable terminal emulation support
vim-pager	Install vimpager and vimmanpager links

vis

tre	more memory efficient regex search using dev-libs/tre

xemacs

athena	Chooses the MIT Athena widget set
dnd	Enables support for the x11-libs/dnd drag-n-drop library
eolconv	Support detection and translation of newline conventions
pop	Support POP for mail retrieval
xim	Enable X11 XiM input method

zile

valgrind	Enable usage of dev-util/valgrind in tests

app-emacs

anything

extensions	Install optional extensions

auctex

preview-latex	Use bundled preview-latex

bbdb

tex	Install plain TeX support files
vm	Add support for app-emacs/vm

calfw

howm	Add support for the app-emacs/howm note-taking tool

company-mode

ropemacs	Install backend for dev-python/ropemacs

emacs-common-gentoo

games	Support shared score files for games

org-mode

contrib	Install user-contributed files
odt-schema	Install non-free schema files for OpenDocument Text exporter

remember

bbdb	Include support for app-emacs/bbdb
planner	Include support for app-emacs/planner

slime

xref	Install xref.lisp cross-referencing tool

vm

bbdb	Include support for app-emacs/bbdb

wanderlust

bbdb	Include support for app-emacs/bbdb

wikipedia-mode

outline-magic	Enable support for outline-mode extensions (app-emacs/outline-magic)

app-emulation

bochs

3dnow	Enable support for emulating 3DNow! instructions (incomplete)
avx	Enable support for emulating Advanced Vector Extensions (AVX)
debugger	Enable debugger (slows down emulation)
gdb	Enable support for the remote GDB stub
x86-64	Enable support for emulation of 64-bit CPUs

buildah

ostree	Enables dependencies for handling of OSTree images.

containerd

apparmor	Support for AppArmor
btrfs	Support for BTRFS snapshot driver
cri	Support for Kubernetes CRI

containers-storage

btrfs	Enables dependencies for the "btrfs" graph driver, including necessary kernel flags.
device-mapper	Enables dependencies for the "devicemapper" graph driver, including necessary kernel flags.
ostree	Enables dependencies for handling of OSTree images.

cri-o

btrfs	Enables dependencies for the "btrfs" graph driver, including necessary kernel flags.
device-mapper	Enables dependencies for the "devicemapper" graph driver, including necessary kernel flags.
ostree	Enables dependencies for handling of OSTree images.

crossover-bin

capi	Enable ISDN support via CAPI
opencl	Enable OpenCL support

docker

apparmor	Enable AppArmor support.
aufs	Enables dependencies for the "aufs" graph driver, including necessary kernel flags.
btrfs	Enables dependencies for the "btrfs" graph driver, including necessary kernel flags.
container-init	Makes the a staticly-linked init system tini available inside a container.
device-mapper	Enables dependencies for the "devicemapper" graph driver, including necessary kernel flags.
overlay	Enables dependencies for the "overlay" graph driver, including necessary kernel flags.
pkcs11	Enables pkcs-11 support.

docker-runc

ambient	Enable support for ambient capability
apparmor	Enable AppArmor support

dosemu

fluidsynth	use media-sound/fluidsynth for MIDI emulation

e-uae

capslib	Add CAPS library support
sdl-sound	Use media-libs/sdl-sound for audio output

free42

alsa	Adds support for Advanced Linux Sound Architecture

fuse

backend-X	Use X11 rendering backend
backend-fbcon	Use framebuffer rendering backend
backend-sdl	Use SDL rendering backend
backend-svga	Use svgalib rendering backend

fuse-utils

gcrypt	Use dev-libs/libgcrypt for low-level crypto of some features, including logfiles.

ganeti

drbd	Enable DRBD support
experimental	Enable experimental patches. Warning! This will break RPC within major versions if the patches applied differ!
haskell-daemons	Build haskell daemons instead of python
htools	Enable htools support
kvm	Enable KVM support
lxc	Enable Linux Countainers support
monitoring	Enable the ganeti monitoring daemon
multiple-users	Enable support for running VMs as different users
rbd	Enable rados block device support via sys-cluster/ceph
restricted-commands	Enable restricted commands in the node daemon
xen	Enable Xen support

hyperd

libvirt	Enable support for KVM via libvirt
xen	Enable support for the Xen Hypervisor

libcacard

passthrough	Enable smartcard passthrough support via sys-apps/pcsc-lite

libguestfs

erlang	Build Erlang bindings
fuse	Enable image mount support via fuse
inspect-icons	Use media-gfx/icoutilsfor acces icon file in image and inspect it
systemtap	Use dev-util/systemtap to inspect VM via "probes" way

libspectrum

gcrypt	Use dev-libs/libgcrypt for low-level crypto of some features, including logfiles.

libvirt

apparmor	Enable AppArmor support
firewalld	DBus interface to iptables/ebtables allowing for better runtime management of your firewall.
fuse	Allow LXC to use sys-fs/fuse for mount points
glusterfs	Enable GlusterFS support via sys-cluster/glusterfs
iscsi	Allow using an iSCSI remote storage server as pool for disk image storage
libssh	Use net-libs/libssh to communicate with remote libvirtd hosts, for example: qemu+libssh://server/system
libvirtd	Builds the libvirtd daemon as well as the client utilities instead of just the client utilities
lvm	Allow using the Logical Volume Manager (sys-fs/lvm2) as pool for disk image storage
lxc	Support management of Linux Containers virtualisation (app-emulation/lxc)
macvtap	Support for MAC-based TAP (macvlan/macvtap). For networking instead of the normal TUN/TAP. It has its advantages and disadvantages. macvtap support requires very new kernels and is currently evolving. Support for this is experimental at best.
nfs	Allow using Network File System mounts as pool for disk image storage
numa	Use NUMA for memory segmenting via sys-process/numactl and sys-process/numad
openvz	Support management of OpenVZ virtualisation (openvz-sources)
parted	Allow using real disk partitions as pool for disk image storage, using sys-block/parted to create, resize and delete them.
pcap	Support auto learning IP addreses for routing
phyp	Support IBM HMC / IVM hypervisor via PHYP protocol
qemu	Support management of QEMU virtualisation (app-emulation/qemu)
rbd	Enable rados block device support via sys-cluster/ceph
uml	Support management of User Mode Linux virtualisation
vepa	Virtual Ethernet Port Aggregator (VEPA) / 802.1Qbg support. Relies on macvtap support.
virt-network	Enable virtual networking (NAT) support for guests. Includes all the dependencies for NATed network mode. Effectively any network setup that relies on libvirt to setup and configure network interfaces on your host. This can include bridged and routed networks ONLY if you are allowing libvirt to create and manage the underlying devices for you. In some cases this requires enabling the 'netcf' USE flag (currently unavailable).
virtualbox	Support management of VirtualBox virtualisation (one of app-emulation/virtualbox or app-emulation/virtualbox-bin)
wireshark-plugins	Build the net-analyzer/wireshark plugin for the Libvirt RPC protocol
xen	Support management of Xen virtualisation (app-emulation/xen)
zfs	Enable ZFS backend storage sys-fs/zfs

lxc

apparmor	Enable AppArmor support
cgmanager	Enable support for cgroup management using app-admin/cgmanager
templates	Install old style templates through app-emulation/lxc-templates

lxd

daemon	Build the system daemon, not just the client tool
dnsmasq	Depend on dnsmasq to provide DHCP and DNS
tools	Build and install optional tools

nemu

ovf	Adds support for OVA/OVF import
savevm	Adds support for QEMU savevm snapshots (experimental, QEMU must be patched)
vnc-client	Adds support for external VNC client

open-vm-tools

caf	Build Common Agent Framework
deploypkg	Build deploypkg plugin
dnet	Enable support for nicinfo
doc	Generate API documentation
fuse	Enable vmblock-fuse/vmhgfs-fuse
grabbitmqproxy	Build grabbitmqproxy plugin
gtkmm	Compile with Gtkmm and sigc++ (Recommended)
multimon	Enable multimon (Requires X)
pic	Force shared libraries to be built as PIC
resolutionkms	Build the linux/unix resolutionkms module
vgauth	Build vgauth
xml-security-c	Build vgauth with xml-security-c instead of xmlsec1
xmlsec	Build vgauth with xmlsec1 instead of xml-security-c

playonlinux

winbind	Enables support for the winbind auth daemon

punes

cg	Add support for Nvidia CG Toolkit

q4wine

ico	Enable ico support via media-gfx/icoutils
iso	Support unprivileged mounting of ISO9660 images via sys-fs/fuseiso
wineappdb	Enable Wine AppDB browser support

qemu

accessibility	Adds support for braille displays using brltty
aio	Enables support for Linux's Async IO
alsa	Enable alsa output for sound emulation
capstone	Enable disassembly support with dev-libs/capstone
curl	Support ISOs / -cdrom directives vis HTTP or HTTPS.
fdt	Enables firmware device tree support
glusterfs	Enables GlusterFS cluster fileystem via sys-cluster/glusterfs
gnutls	Enable TLS support for the VNC console server. For 1.4 and newer this also enables WebSocket support. For 2.0 through 2.3 also enables disk quorum support.
gtk2	Use gtk-2 instead of gtk-3
iscsi	Enable direct iSCSI support via net-libs/libiscsi instead of indirectly via the Linux block layer that sys-block/open-iscsi does.
jpeg	Enable jpeg image support for the VNC console server
ncurses	Enable the ncurses-based console
nfs	Enable NFS support
numa	Enable NUMA support
pin-upstream-blobs	Pin the versions of BIOS firmware to the version included in the upstream release. This is needed to sanely support migration/suspend/resume/snapshotting/etc... of instances. When the blobs are different, random corruption/bugs/crashes/etc... may be observed.
png	Enable png image support for the VNC console server
pulseaudio	Enable pulseaudio output for sound emulation
rbd	Enable rados block device backend support, see http://ceph.newdream.net/wiki/QEMU-RBD
sdl	Enable the SDL-based console
sdl2	Use libsdl2 instead of libsdl
snappy	Enable support for snappy compression
spice	Enable Spice protocol support via app-emulation/spice
ssh	Enable SSH based block device support via net-libs/libssh2
static	Build the User and Software MMU (system) targets as well as tools as static binaries
static-user	Build the User targets as static binaries
systemtap	Enable SystemTAP/DTrace tracing
tci	Enable the TCG Interpreter which can speed up or slowdown workloads depending on the host and guest CPUs being emulated. In the future it will be a runtime option but for now its compile time.
usb	Enable USB passthrough via dev-libs/libusb
usbredir	Use sys-apps/usbredir to redirect USB devices to another machine over TCP
vde	Enable VDE-based networking
vhost-net	Enable accelerated networking using vhost-net, see http://www.linux-kvm.org/page/VhostNet
virgl	Enable experimental Virgil 3d (virtual software GPU)
virtfs	Enable VirtFS via virtio-9p-pci / fsdev. See http://wiki.qemu.org/Documentation/9psetup
vte	Enable terminal support (x11-libs/vte) in the GTK+ interface
xattr	Add support for getting and setting POSIX extended attributes, through sys-apps/attr. Requisite for the virtfs backend.
xen	Enables support for Xen backends
xfs	Support xfsctl() notification and syncing for XFS backed virtual disks.

qt-virt-manager

smartcard	Enable smartcard remoting using app-emulation/libcacard

rkt

actool	Install the actool for ACI manipulation
rkt_stage1_coreos	Download and use a prebuilt stage1.aci from CoreOS
rkt_stage1_fly	Build stage1-fly.aci
rkt_stage1_host	Assemble stage1.aci from host binaries
rkt_stage1_kvm	This flag has been replaced by the rkt_stage1_kvm_* flags
rkt_stage1_kvm_lkvm	Build stage1-kvm-lkvm.aci
rkt_stage1_kvm_qemu	Build stage1-kvm-qemu.aci
rkt_stage1_src	Build the stage1.aci from source

runc

ambient	Enable support for ambient capabilities set (Requires Linux kernel 4.3 or later).
apparmor	Enable AppArmor support.

runv

libvirt	Enable support for KVM via libvirt
xen	Enable support for the Xen Hypervisor

spice

lz4	Enable support for LZ4 compression using app-arch/lz4
smartcard	Enable smartcard remoting using app-emulation/libcacard

spice-vdagent

consolekit	Use sys-auth/consolekit to determine the master vdagentd in case of multiple running vdagentds (highly recommended)

uae

scsi	Enable the uaescsi.device

vagrant

virtualbox	Use VirtualBox provider.

vice

ethernet	Enable ethernet emulation
fullscreen	Enable the ability to run fullscreen
sdlsound	Use media-libs/libsdl for sound support
vte	Enable support for x11-libs/vte in the GTK+ interface

virt-manager

policykit	Enables sys-auth/polkit authentication support, required when using app-emulation/libvirt with PolicyKit authentication
sasl	Depend on the proper libraries needed to connect to SASL-enabled libvirtd instances (e.g. Kerberos-protected instances).

virt-viewer

spice	Support connecting to SPICE-enabled virtual machines.
vnc	Support connecting to VNC-enabled virtual machines.

virt-what

dmi	Use sys-apps/dmidecode to read firmware data

virtualbox

headless	Build without any graphic frontend
lvm	Build VBoxVolInfo that needs devicemapper from sys-fs/lvm2.
opus	Adds support for the Opus codec via media-libs/opus
pax_kernel	Apply patch needed for pax enabled kernels.
sdk	Enable building of SDK
udev	Controls installation of special USB udev rules.
vboxwebsrv	Build and install the VirtualBox webservice

virtualbox-bin

additions	Install Guest System Tools ISO
chm	Install kchmviewer binary to enable online help (in MS CHM format)
headless	Install without any graphic frontend
rdesktop-vrdp	Install the rdesktop client integration
sdk	Enable building of SDK
vboxwebsrv	Install the VirtualBox webservice

virtualbox-modules

pax_kernel	Apply patch needed for pax enabled kernels

vkd3d

spirv-tools	Enable SPIRV shader debugging support using dev-util/spirv-tools

vov

gprof	build with profiling support

wine-any

capi	Enable ISDN support via CAPI
custom-cflags	Bypass strip-flags; use at your own peril
d3d9	Apply highly experimental patches for Gallium Nine support. This patch may break some applications.
dos	Pull in games-emulation/dosbox to run DOS applications
ffmpeg	Use media-video/ffmpeg to decode WMA formats
gecko	Add support for the Gecko engine when using iexplore
gssapi	Use GSSAPI (Kerberos SSP support)
gstreamer	Use media-libs/gstreamer to provide DirectShow functionality;
mono	Add support for .NET using Wine's Mono add-on
netapi	Use libnetapi from net-fs/samba to support Windows networks in netapi32.dll
opencl	Enable OpenCL support
osmesa	Add support for OpenGL in bitmaps using libOSMesa
pcap	Support packet capture software (e.g. wireshark)
perl	Install helpers written in perl (winedump/winemaker)
pipelight	Apply Wine-Staging patches for Pipelight/Silverlight support
prelink	Run prelink on DLLs during build; For versions before wine-1.7.55 or hardened, do not disable if you do not know what this means as it can break things at runtime
realtime	Pull in sys-auth/rtkit for low-latency pulseaudio support
run-exes	Use Wine to open and run .EXE and .MSI files
samba	Add support for NTLM auth. see http://wiki.winehq.org/NtlmAuthSetupGuide and http://wiki.winehq.org/NtlmSigningAndSealing
sdl	Add support for gamepad detection using SDL
staging	Apply Wine-Staging patches for advanced feature support that haven't made it into upstream Wine yet
themes	Support GTK+:3 window theming through Wine-Staging
udev	Use virtual/libudev to provide plug and play support
vkd3d	Use app-emulation/vkd3d to provide Direct3D 12 support
vulkan	Enable Vulkan drivers

wine-d3d9

capi	Enable ISDN support via CAPI
custom-cflags	Bypass strip-flags; use at your own peril
d3d9	Apply highly experimental patches for Gallium Nine support. This patch may break some applications.
dos	Pull in games-emulation/dosbox to run DOS applications
gecko	Add support for the Gecko engine when using iexplore
gssapi	Use GSSAPI (Kerberos SSP support)
gstreamer	Use media-libs/gstreamer to provide DirectShow functionality;
mono	Add support for .NET using Wine's Mono add-on
netapi	Use libnetapi from net-fs/samba to support Windows networks in netapi32.dll
opencl	Enable OpenCL support
osmesa	Add support for OpenGL in bitmaps using libOSMesa
pcap	Support packet capture software (e.g. wireshark)
perl	Install helpers written in perl (winedump/winemaker)
prelink	Run prelink on DLLs during build; For versions before wine-1.7.55 or hardened, do not disable if you do not know what this means as it can break things at runtime
realtime	Pull in sys-auth/rtkit for low-latency pulseaudio support
run-exes	Use Wine to open and run .EXE and .MSI files
samba	Add support for NTLM auth. see http://wiki.winehq.org/NtlmAuthSetupGuide and http://wiki.winehq.org/NtlmSigningAndSealing
sdl	Add support for gamepad detection using SDL
udev	Use virtual/libudev to provide plug and play support
vkd3d	Use app-emulation/vkd3d to provide Direct3D 12 support
vulkan	Enable Vulkan drivers

wine-staging

capi	Enable ISDN support via CAPI
custom-cflags	Bypass strip-flags; use at your own peril
dos	Pull in games-emulation/dosbox to run DOS applications
ffmpeg	Use media-video/ffmpeg to decode WMA formats
gecko	Add support for the Gecko engine when using iexplore
gssapi	Use GSSAPI (Kerberos SSP support)
gstreamer	Use media-libs/gstreamer to provide DirectShow functionality;
mono	Add support for .NET using Wine's Mono add-on
netapi	Use libnetapi from net-fs/samba to support Windows networks in netapi32.dll
opencl	Enable OpenCL support
osmesa	Add support for OpenGL in bitmaps using libOSMesa
pcap	Support packet capture software (e.g. wireshark)
perl	Install helpers written in perl (winedump/winemaker)
pipelight	Apply Wine-Staging patches for Pipelight/Silverlight support
prelink	Run prelink on DLLs during build; For versions before wine-1.7.55 or hardened, do not disable if you do not know what this means as it can break things at runtime
realtime	Pull in sys-auth/rtkit for low-latency pulseaudio support
run-exes	Use Wine to open and run .EXE and .MSI files
samba	Add support for NTLM auth. see http://wiki.winehq.org/NtlmAuthSetupGuide and http://wiki.winehq.org/NtlmSigningAndSealing
sdl	Add support for gamepad detection using SDL
staging	Apply Wine-Staging patches for advanced feature support that haven't made it into upstream Wine yet
themes	Support GTK+:3 window theming through Wine-Staging
udev	Use virtual/libudev to provide plug and play support
vkd3d	Use app-emulation/vkd3d to provide Direct3D 12 support
vulkan	Enable Vulkan drivers

wine-vanilla

capi	Enable ISDN support via CAPI
custom-cflags	Bypass strip-flags; use at your own peril
dos	Pull in games-emulation/dosbox to run DOS applications
gecko	Add support for the Gecko engine when using iexplore
gssapi	Use GSSAPI (Kerberos SSP support)
gstreamer	Use media-libs/gstreamer to provide DirectShow functionality;
mono	Add support for .NET using Wine's Mono add-on
netapi	Use libnetapi from net-fs/samba to support Windows networks in netapi32.dll
opencl	Enable OpenCL support
osmesa	Add support for OpenGL in bitmaps using libOSMesa
pcap	Support packet capture software (e.g. wireshark)
perl	Install helpers written in perl (winedump/winemaker)
prelink	Run prelink on DLLs during build; For versions before wine-1.7.55 or hardened, do not disable if you do not know what this means as it can break things at runtime
realtime	Pull in sys-auth/rtkit for low-latency pulseaudio support
run-exes	Use Wine to open and run .EXE and .MSI files
samba	Add support for NTLM auth. see http://wiki.winehq.org/NtlmAuthSetupGuide and http://wiki.winehq.org/NtlmSigningAndSealing
sdl	Add support for gamepad detection using SDL
udev	Use virtual/libudev to provide plug and play support
vkd3d	Use app-emulation/vkd3d to provide Direct3D 12 support
vulkan	Enable Vulkan drivers

winetricks

rar	Pull in app-arch/unrar for extraction of rar-compressed game files

x48

readline	Enables support for libreadline

xe-guest-utilities

xenstore	Use xenstore binaries bundled by Citrix instead of building app-emulation/xen-tools

xen

efi	Adds efi boot support, requires LDFLAG -melf_x86_64 for amd64
flask	Enable the Flask XSM module from NSA

xen-tools

api	Build the C libxenapi bindings
flask	Enable the Flask XSM module from NSA
hvm	Enable support for hardware based virtualization (VT-x,AMD-v)
ocaml	Enable support for the ocaml language
ovmf	Enable support to boot UEFI guest vm, needed by hvm
pam	Enable pam support
pygrub	Install the pygrub boot loader
qemu	Enable IOEMU support via the use of qemu-dm
qemu-traditional	Build the old qemu traditional device model (useful only if you cannot change to the new device model e.g. Windows VMs)
screen	Enable support for running domain U console in an app-misc/screen session
system-qemu	Using app-emulation/qemu instead of the bundled one
system-seabios	Using sys-firmware/seabios instead of the bundled one

xtrs

ls-dos	Install LS-DOS disk images for Model 4P

app-eselect

eselect-php

fpm	Enable the FastCGI Process Manager SAPI

app-forensics

afflib

fuse	Enable extra fuse thingies
qemu	Enable qemu stuff
s3	Enable support for Amazon S3

aide

e2fs	Enable support for checking file attributes on ext2/ext3/ext4 filesystems
prelink	Bypass prelinking when calculating checksums

chkrootkit

cron	Install cron script for weekly rootkit scans

libewf

bfio	Enables libbfio for chaining file in file handling
ewf	Enables the v1 API
fuse	Enable fuse support for ewfmount
rawio	Enables raw IO handling
uuid	Enable UUID support in the ewftools

openscap

gconf	Build the gconf independant probes
nss	Prefer NSS over libgcrypt as the crypto engine
rpm	Compiles the RPM probes
sce	Enables Script Check Engine (SCE) support
sql	Build the sql independant probes

quickfuzz

archs	support archive formats
codes	support cource code formats
docs	support document formats
imgs	support image formats
media	support media formats
net	support networking formats
pki	support PKI formats

sleuthkit

aff	Enable extra aff formats
ewf	Enable libewf support

app-i18n

anthy

canna-2ch	Enable support for app-dicts/canna-2ch

canna

canuum	Build canuum

fcitx

autostart	Enable XDG-compatible autostart of Fcitx
enchant	Enable Enchant backend (using app-text/enchant) for spelling hinting
gtk2	Install input method module for GTK+ 2
gtk3	Install input method module for GTK+ 3
opencc	Enable OpenCC engine (using app-i18n/opencc) for converter between Simplified Chinese and Traditional Chinese
pango	Enable support for x11-libs/pango
table	Install table input methods for Simplified Chinese

fcitx-libpinyin

dictionary-manager	Install dictionary manager

fcitx-rime

configuration_tool	Install configuration tool

fcitx-unikey

macro-editor	Install macro editor

freewnn

uum	Build uum

ibus

emoji	Enable support for Emoji
gconf	Enable support for gnome-base/gconf
gtk2	Enable support for x11-libs/gtk+:2
unicode	Enable support for Unicode choice

ibus-chewing

gconf	Enable support for gnome-base/gconf

ibus-handwrite

zinnia	Enable support for app-i18n/zinnia

ibus-libpinyin

boost	Compile against dev-libs/boost libraries
opencc	Enable support for app-i18n/opencc

ibus-m17n

gtk2	Build with x11-libs/gtk+:2 instead of x11-libs/gtk+:3

ibus-pinyin

boost	Enable support for dev-libs/boost

ibus-unikey

gtk2	Enable support for x11-libs/gtk+:2

im-chooser

gtk2	Build with x11-libs/gtk+:2 instead of x11-libs/gtk+:3
xfce	Enable support for XFCE panel

imsettings

gconf	Enable support for gnome-base/gconf
gtk2	Build with x11-libs/gtk+:2 instead of x11-libs/gtk+:3
xfconf	Enable support for xfce-base/xfconf

mozc

fcitx4	Enable support for app-i18n/fcitx 4
gui	Install graphical user interface tool (mozc_tool)
handwriting-tegaki	Use handwriting recognition model from app-i18n/tegaki-zinnia-japanese
handwriting-tomoe	Use handwriting recognition model from app-i18n/zinnia-tomoe
ibus	Enable support for app-i18n/ibus
renderer	Enable native candidate window

pyzy

boost	Enable support for dev-libs/boost
doc	Generate API documentation
opencc	Enable support for app-i18n/opencc

rime-data

extra	Install extra packages

scim

gtk3	Enable support for x11-libs/gtk+:3

scim-anthy

gtk3	Enable support for x11-libs/gtk+:3
kasumi	Use Anthy dictionary maintenance tool (app-dicts/kasumi)

scim-sunpinyin

gtk3	Enable support for x11-libs/gtk+:3

tomoe

hyperestraier	Enable support for app-text/hyperestraier

translate-shell

tts	Enable text-to-speech support

uim

anthy	Enable support for app-i18n/anthy
eb	Enable support for dev-libs/eb
gtk2	Enable support for x11-libs/gtk+:2
skk	Enable support for app-i18n/skk-jisyo

app-laptop

hdapsd

libconfig	Require dev-libs/libconfig to allow the daemon to read a configuration file at startup

ibam

gkrellm	Enable building of app-admin/gkrellm module

pbbuttonsd

ibam	Enable support for Intelligent Battery Monitoring
macbook	Enable support for the Macbook and Macbook Pro

thinkfan

atasmart	include libatasmart support to get disc temperature

tp_smapi

hdaps	Install a compatible HDAPS module

app-leechcraft

lc-azoth

acetamide	Build Acetamide, the IRC protocol support
adiumstyles	Build support for Adium styles
astrality	Build Astrality, support for protocols provided by Telepathy
autoidler	Build support for automatic status changing according to user idle time
autopaste	Build Autopaste for pasting long texts to pastebins
birthdaynotifier	Build Birthday Notifier for you to not forget about birthdays of your contacts.
chathistory	Build ChatHistory which stories chat history
depester	Build Depester which enables to ignore MUC participants
embedmedia	Build EmbedMedia for embedding flash videos and images directly into chat windows
herbicide	Build Herbicide, a basic antispam plugin
hili	Build HiLi which allows to customize highlight settings in MUCs
isterique	Build Isterique plugin for neutralizing excessive caps lock usage
juick	Build plugin for the Juick.com microblogging service
keeso	Build plugin for changing text into SoMEtHInG lIKe THiS
lastseen	Build plugin for client-side recording of the last online/available time
media	Enable media calls
metacontacts	Build plugin for metacontacts support
murm	Build Murm, the VKontakte messaging support via their native API (instead of XMPP)
nativeemoticons	Build support for native Azoth's emoticons packs
otroid	Build OTRoid, plugin for the Off-the-Record deniable encryption system
sarin	Build Sarin, Tox protocol support module. Please add mva overlay to use net-libs/tox
shx	Build shell command executor plugin
standardstyles	Build support for standard Azoth styles engine
vader	Bulid Vader, the MRIM (Mail.Ru Agent) protocol support plugin
velvetbird	Build support for protocols provided by libpurple
woodpecker	Build Woodpecker, the Twitter client plugin
xtazy	Build Xtazy for publishing currently playing tune

lc-blasq

deathnote	Support LiveJournal FotoBilder service
rappor	Support VKontakte service
spegnersi	Support Flickr service
vangog	Support Picasa service

lc-blogique

hestia	Allows one to keep a local blog
metida	Support for the LiveJournal blogging platform

lc-core

qwt	Support for QML plotting item through x11-libs/qwt

lc-gmailnotifier

notify	Pull in a plugin to show notifications from GMail Notiifer
quark	Pull in a plugin to show GMail Notifier's quark

lc-lmp

fradj	Build FrAdj, the equalizer effect module
graffiti	Build media tags editor plugin
mp3tunes	Build plugin for supporting the mp3tunes.com music locker service
mpris	Enable MPRIS support
potorchu	Enable the projectM-based visualization effects module for LMP

lc-monocle

fb2	Enable support for FictionBook format
mobi	Enable support for MOBI format

lc-musiczombie

acoustid	Use media-libs/chromaprint for acoustic fingerprinting

lc-netstoremanager

dropbox	Build Dropbox storage backend
googledrive	Build Google Drive storage backend

lc-poshuku

autosearch	Provide automatic search suggestions for Poshuku.
cleanweb	Build CleanWeb for ad blocking compatible with Firefox's AdBlock+.
dcac	Build color inverter module providing a night mode.
fatape	Build FatApe, GreaseMonkey userscripts support layer.
filescheme	Build FileScheme for accessing local URLs.
foc	Build FOC for Flash-on-Click functionality.
fua	Build FUA for faking user agents for different hosts.
keywords	Build Keywords for adjusting search shortcuts.
onlinebookmarks	Build OnlineBookmarks for syncing bookmarks with social bookmarking services like Read It Later.
qrd	Build module for displaying the QR code of a web page.
speeddial	Build SpeedDial module.
webengine	Build WebEngine- (that is, Chromium-)based rendering backend.

lc-secman

exposecontents	Build the GUI for viewing the stored data.

leechcraft-meta

de	Install components, that allow using Leechcraft as Desktop Environment

app-metrics

collectd

contrib	Install user-contributed files in the doc directory
filecaps	When set collectd daemon will have set required capabilities to run most plugins even if run as unprivileged user
java	Must be set (workaround for java-pkg-opt-2 eclass limitation) when you want java or genericjmx plugin
udev	Enable optional udev usage in disk plugin; Required for smart plugin
xfs	Enable optional capability to filter on XFS file system in df plugin; Requires XFS headers from sys-fs/xfsprogs

app-misc

anki

recording	Enable support for audio recording
sound	Enable support for adding sound to cards

binwalk

graph	Enable support for generating entropy graphs

blink1

mini-tool	Build and install command-line mini-tool blink1-mini-tool (normally used for embedded devices)
server	Build and install REST API server (currently hard-coded to TCP port 8080)
tool	Build and install command-line tool blink1-tool

byobu

screen	Use app-misc/screen as the default backend

ca-certificates

cacert	Include root certificates from CAcert (http://www.cacert.org/) and Software in the Public Interest (http://www.spi-inc.org/)
insecure_certs	Install certificates which are known to be untrustworthy.

carbon-c-relay

lz4	add support for LZ4 compressed transport
oniguruma	use dev-libs/oniguruma as regex implementation
pcre2	use dev-libs/libpcre2 as regex implementation

ddccontrol

pci	enable direct PCI memory access (the setuid ddcpci util)

ddcutil

drm	Use x11-libs/libdrm for more verbose diagnostics.
usb-monitor	Adds support for monitors attached via USB.
user-permissions	Adds a udev rules to allow non-root users in the i2c group to access the /dev/i2c-* devices. If usb-monitor is selected, users will need to be added to the video group to access the USB monitor. Otherwise, only root will be able to use ddcutil.

digitemp

ds2490	Build support for the ds2490 sensor
ds9097	Build support for the ds9097 sensor
ds9097u	Build support for the ds9097u sensor

elasticsearch

x-pack	Enable additional features (may need a license)

emelfm2

ansi	Add support for ANSI escape sequences
gtk3	Use x11-libs/gtk+:3 instead of x11-libs/gtk+:2

freemind

groovy	Build plugin for scripting via Groovy
latex	Build plugin for inserting mathematical formulas in LaTeX syntax
pdf	Build plugin for exporting mindmaps to SVG and PDF
svg	Build plugin for exporting mindmaps to SVG and PDF

g810-led

hidapi	Use dev-libs/hidapi instead of virtual/libusb for talking to the device (advertised to be faster)

gcstar

stats	Enable statistics reporting
tellico	Enable support for kde-misc/tellico files

geoclue

geonames	Install geonames.org provider
gsmloc	Install GSM location provider
gtk	Install gtk-based geoclue-test-gui
hostip	Install hostip.info provder
manual	Install manual provider
modemmanager	Enable geolocation through 3G or GPS enabled hardware through net-misc/modemmanager.
nominatim	Install openstreetmap.org provider
plazes	Install plazes.com provider
skyhook	Install skyhookwireless.com provider
yahoo-geo	Install Yahoo geolocation provider
zeroconf	Enable retrieval of GPS location from Android devices with https://wiki.gnome.org/Apps/GeoclueShare

gourmet

i18n	Enable support for i18n through elib.intl
ipython	Enable support for the interactive Python console plugin
pdf	Enable export to PDF
print	Enable pretty Python printing
spell	Enable support for the spell check plugin
web	Enable support for the web import plugin

gramps

geo	Enable rendering of geographical data using sci-geosciences/osm-gps-map
rcs	Adds support for family tree archives via dev-vcs/rcs
reports	All external software that is needed for graphical reports will be installed

graphlcd-base

g15	Add support for app-misc/g15daemon driver (e.g. Logitech G15 Keybord)

irtrans-irserver

mono	Enable mono support

jq

oniguruma	Use dev-libs/oniguruma for regular expression support

kryoflux-dtc

demos	Install example floppy game files.
fast-firmware	Install fast firmware instead of slow firmware.
gui	Install the Kryoflux GUI

lcd4linux

apm	Enable the APM plugin.
asterisk	Enable the Asterisk plugin.
button_exec	Enable the Button plugin, to execute something on keypress.
cpuinfo	Enable the cpuinfo plugin.
dbus	Enable the dbus plugin.
diskstats	Enable the diskstats plugin.
dmalloc	Enable dmalloc for debugging.
dvb	Enable support for the DVB plugin.
event	Enable the event plugin.
exec	Enable the exec plugin, to read output from external programs.
fifo	Enable the FIFO (First-In, First-Out) plugin.
file	Enable the file plugin, to read from input from files.
gps	Enable the gps plugin, for reading gps coordinates.
hddtemp	Enable the hddtemp plugin, to read from the hddtemp daemon.
huawei	Enable the huawei plugin, to read from a huawei device.
i2c_sensors	Enable the i2c_sensors plugin, to read sensor data.
iconv	Enable the iconv plugin, to convert between encodings.
isdn	Enable the isdn plugin, to get information about ISDN.
kvv	Enable the kvv plugin, to get realtime train schedule from the Karlsruher Verkehrsverbund.
loadavg	Enable the loadavg plugin, to get stats load
meminfo	Enable the meminfo plugin, to get memory statistics.
mpd	Enable the mpd plugin, to read from the Music Player Daemon.
mpris_dbus	Enable the mpris plugin, to read data via dbus for mpris.
mysql	Enable the mysql plugin, to get mysql database information.
netdev	Enable the netdev plugin, to get interface statistics.
netinfo	Enable the netinfo plugin, to get more interface statistic.
outb	Enable raw i/o access.
pop3	Enable the pop3 plugin, to get notified about new mails.
proc_stat	Enable the proc_stat plugin, to read data from the proc file system.
python	Enable support for dev-lang/python and enable the python plugin, to execute own python scripts.
qnaplog	Enable the qnaplog plugin, to read a log from a QNAP device.
raspi	Enable the raspi plugin, to read sensor data from a Raspberry Pi.
sample	Enable the sample plugin.
statfs	Enable the statfs plugin, to get statistics about the file system.
uname	Enable the uname plugin, to get the output of uname.
uptime	Enable the uptime plugin.
w1retap	Enable the w1retap plugin.
wireless	Enable the wireless plugin, to get wireless statistics.

lcdproc

ftdi	Enable support for FTDI connections in some selected LCD_DEVICES (currently hd44780)
hid	Enable HID support using libhid
irman	Enable support for IRMan (media-libs/libirman)
lcd_devices_sdeclcd	Enable support for VLSYS M428 display
lcd_devices_vlsys_m428	Enable support for VLSYS M428 display
nfs	Adds support for NFS file system
seamless-hbars	Try to avoid gaps in horizontal bars

lirc

audio	Support using an audio device connected to an IR receiver
devinput	Support the devinput input device
ftdi	Support FTDI devices
gtk	Include GTK support which enables the use of lirc-setup
hardware-carrier	The transmitter device generates its clock signal in hardware
inputlirc	Add a dependency on app-misc/inputlircd
transmitter	Add transmitter support to some lirc-drivers (e.g. serial)
uinput	Enable support for uinput

mc

edit	Compile and install the mcedit application
mclib	Compile and install the libmc.so shared library
sftp	Add support for sftp (uses net-libs/libssh2 for it).
slang	Use sys-libs/slang instead of sys-libs/ncurses.
xdg	Toggles mc's config dir location. Enable for $XDG_CONFIG_HOME/mc, disable for $HOME/.mc

mosquitto

bridge	Enable bridge support in the MQTT broker.
persistence	Store messages and subscriptions to a file.
srv	Include SRV lookup support.
websockets	Support the WebSocket protocol.

muttprint

doc	Builds documentation

neofetch

X	Enable support for detecting DEs, WMs, screen resolutions, and showing images from an X terminal

nnn

fish-completion	Enable fish completion support

note

general	Add support for ascii flatfile backend
text	Add support for text backend

openastro

jpeg	Enable exporting Astrological Charts to jpeg
png	Enable exporting Astrological Charts to png

pax-utils

python	Install a more powerful/faster version of lddtree

recoll

camelcase	Enable indexing for camelCase sentences and words
inotify	Use the Linux Kernel notification subsystem for monitoring file alterations in realtime
session	Stop monitoring file alterations when X11 session terminates

rlwrap

debug	Enable debug

screen

multiuser	Enable multiuser support (by setting correct permissions)
nethack	Express error messages in nethack style
utmp	Include utmp support

screenfetch

X	Use the media-gfx/scrot package to take screenshots

skim

tmux	Install sk-tmux script to run skim in a tmux pane
vim	Install vim plugin for skim

sphinx

id64	use 64-bit document and word IDs
mariadb	Add mariadb database support
re2	use the dev-libs/re2 regular expression library
stemmer	Enable language stemming support

task

sync	Enable "task sync" support

tmux

utempter	Include libutempter support

towitoko

moneyplex	Makes libtowitoko work for the moneyplex home banking software

tracker

cue	Enable cue sheet parsing
firefox-bookmarks	Install bookmark data miner plugin for www-client/firefox and www-client/firefox-bin
gsf	Enable gnome-extra/libgsf based data extractor and for ODT.
iptc	Enable extraction of IPTC data from pictures
iso	Enable extraction of metadata from ISO disk images
miner-fs	Enable tracker-miner-fs (required for filesystem indexing)
nautilus	Enable tracker to integrate with gnome-base/nautilus by providing entries in its context menu
playlist	Add support for playlists
stemmer	Add word stemming via dev-libs/snowball-stemmer.
thunderbird	Install email data miner plugin for mail-client/thunderbird and mail-client/thunderbird-bin
xps	Add support for XPS file format through app-text/libgxps.

unfoo

minimal	Do not install all support archive binaries

vcontrold

man	Build the manpages
vclient	Build the vclient helper program to talk to vcontrold
vsim	Build the vsim helper program (simulates the heating's answers, for development and debugging)

vifm

X	Add support for X11
developer	Enable features of interest to developers
extended-keys	Support for extended keys (arrows, home etc)
gtk	Use gtk+ to determine mimetypes
magic	Use libmagic to determine mimetypes
vim	Install the vifm vim plugin and vim-compatible documentation
vim-syntax	Pulls in related vim syntax scripts

worker

avfs	Enable support for sys-fs/avfs
magic	Add magic file support from sys-apps/file to automatically detect file types

workrave

mate	Add support for MATE panel
xfce	Add support for XFCE panel

zygrib

maps	Installs additional GSHHS maps for high resolution coastline data and cities

app-mobilephone

gammu

bluetooth	Enables bluetooth support
curl	Enables curl support
irda	Enables infrared support
mysql	Use mysql for data storage
nls	Enable native language support
odbc	Use ODBC as DB connector
postgres	Use PostgreSQL for data storage
usb	Enable USB suport

gnokii

ical	Enable support for dev-libs/libical
irda	Enable infrared support
pcsc-lite	Enable smartcard support with sys-apps/pcsc-lite
sms	Enable SMS support (build smsd)

smstools

stats	Enable statistic reporting

app-office

abiword

collab	Enable collaborative editing plugin
goffice	Enable goffice plugin
grammar	Enable grammar checking via dev-libs/link-grammar
map	Enable world map support through media-libs/libchamplain
math	Enable support for x11-libs/gtkmathview
ots	Enable Text Summarizer plugin
plugins	Enable plugins build (see http://www.abisource.com/wiki/PluginMatrix for more information). If your file cannot be opened due lack of support, try enabling this.
redland	Enables support redland and raptor libs.
thesaurus	Enable thesaurus support
wordperfect	Enable wordperfect file support via app-text/libwpd

calligra

activities	Enable kactivities support
gemini	Enable tablet and 2:1 devices support
import-filter	Enable support for various import filter file formats like WordPerfect, Visio and Apple Keynote
lcms	Build colorengine plugins using media-libs/lcms
okular	Enable bindings for kde-apps/okular
phonon	Build stage/eventplugins and videoshape plugin using media-libs/phonon
pim	Enable support for KDE PIM resources integration
spacenav	Enable support for the 3Dconnexion spacenav input device via dev-libs/libspnav

glabels

barcode	Enable barcode support through external libraries.

gnucash

aqbanking	Connect to some internet banks via AqBanking
chipcard	Enable support for chipcard reading and processing.
gui	Enable graphic interface (needs net-libs/webkit-gtk:4 and x11-libs/gtk+:3)
quotes	Enable Online Stock Quote retrieval
register2	Use the new register (Experimental)

gnumeric

libgda	Enable database support through gnome-extra/libgda.
perl	Enable perl plugin loader.
python	Enable python plugin loader.

kexi

experimental	Enable features deemed experimental by upstream
marble	Enable displaying of maps using kde-apps/marble
mdb	Enable support for Microsoft Access database
webkit	Enable web form designer widget using dev-qt/qtwebkit

kmymoney

activities	Enable kde-frameworks/kactivities integration
addressbook	Enable kde-apps/akonadi contact integration
hbci	Enable HBCI support using net-libs/aqbanking
holidays	Enable kde-frameworks/kholidays integration
quotes	Enable Online Stock Quote retrieval
weboob	Enable import of online banking transactions extracted by www-client/weboob

kraft

pim	Enable support for KDE PIM resources integration

libreoffice

coinmp	Use sci-libs/coinor-mp as alternative solver
googledrive	Enable support for remote files on Google Drive
gtk2	Enable legacy gtk2 frontend
jemalloc	Use dev-libs/jemalloc for allocations
odk	Build the Office Development Kit
pdfimport	Enable PDF import via the Poppler library
vlc	Use media-video/vlc for video embedding

libreoffice-l10n

offlinehelp	Install help files locally instead of using the LibreOffice Wiki

lyx

aspell	Add support for aspell spellchecking
dia	Add support for diagrams (app-office/dia)
docbook	Add support for docbook export
dot	Add support for DOT import (media-gfx/graphviz)
enchant	Add support for enchant spellchecking wrapper (both aspell and hunspell can be used by LyX).
gnumeric	Add support for importing Gnumeric/OpenOffice/MS Excel spreadsheets into LyX.
html	Add support for HTML import
hunspell	Add support for spellchecking based on hunspell and reuse system-wide OpenOffice dictionaries. This also enable thesaurus dictionaries not accessible via aspell.
monolithic-build	This should speed up compilation significantly when you have enough RAM (> 600 MB)
rcs	Add support for revision control via dev-vcs/rcs
rtf	Add support for RTF import/export packages

magicpoint

contrib	Install additional contributed scripts

orage

clock-panel-plugin	Build the clock plugin for the XFCE panel

scribus

boost	Enable support for Boost based enhancement
hunspell	Enable support for spell checking with app-text/hunspell
minimal	Don't install headers (only required for e.g. plug-in developers)
osg	3D redering via dev-games/openscenegraph
scripts	Install the scripts
templates	Document tamplates
tk	Install tk based scripts e.g. FontSample.py

skrooge

activities	Enable kactivities support
designer	Build plugins for dev-qt/designer

texmacs

netpbm	Add support for media-libs/netpbm

texstudio

video	Use phonon for video embedding

wps-office

sharedfonts	Install WPS fonts available system wide

app-pda

barry

boost	Enable boost support
gui	Install the GUI backup tool

gtkpod

clutter	Enable clutter support for displaying coverart

app-portage

conf-update

colordiff	Use colors when displaying diffs (app-misc/colordiff)
libressl	Enable SSL connections and crypto functions using dev-libs/libressl

eix

debug	Build with upstream's CXXFLAGS/LDFLAGS for debugging support; not recommended for normal use.
doc	Create description of the eix cache file additionally in html format
sqlite	Compile in support for portage's sqlite backend; to actually use it you need additional configuration of portage and eix

g-sorcery

bson	Support BSON file format for package DB

gemato

blake2	Install dependencies needed for BLAKE2 hash functions
gpg	Install dependencies needed for OpenPGP signature verification support
sha3	Install dependencies needed for SHA3 hash functions
tools	Install additional utilities (benchmarks, hash testing tools, fast Manifest generators) to /usr/share/gemato.

grs

server	Install all the tools building systems

layman

bazaar	Support dev-vcs/bzr based overlays
cvs	Support dev-vcs/cvs based overlays
darcs	Support dev-vcs/darcs based overlays
g-sorcery	Support app-portage/g-sorcery based overlays
git	Support dev-vcs/git based overlays
gpg	Support app-crypt/gnupg signed overlays lists and manifests
mercurial	Support dev-vcs/mercurial based overlays
squashfs	Support mounting squashfs image overlays locally read-only
subversion	Support dev-vcs/subversion based overlays
sync-plugin-portage	Install the sys-apps/portage sync module

pfl

network-cron	Adds a cron job which does a weekly submit of the package database

tatt

templates	Install template scripts to be used with tatt

app-shells

autojump

ipython	Add support for dev-python/ipython

bash

bashlogger	Log ALL commands typed into bash; should ONLY be used in restricted environments such as honeypots
mem-scramble	Build with custom malloc/free overwriting allocated/freed memory
net	Enable /dev/tcp/host/port redirection
plugins	Add support for loading builtins at runtime via 'enable'

dash

vanilla	Support echo -n, and enable echo -e all the time (unsupported)

pdsh

rsh	This allows the use of rsh (remote shell) and rcp (remote copy) for authoring websites. sftp is a much more secure protocol and is preferred.

shish

diet	Use dev-libs/dietlibc

app-text

asciidoc

highlight	Enable source code highlighting

atril

caja	Enable property page extension in mate-base/caja
dvi	Enable build-in DVI viewer
epub	Enable build-in DVI viewer using net-libs/webkit-gtk
gtk3	Build with GTK+3 instead of GTK+2
t1lib	Enable the Type-1 fonts for the build-in DVI viewer (media-libs/t1lib)
xps	Enable XPS viewer using app-text/libgxps

blogc

git	Build blogc-git-receiver tool
httpd	Build blogc-runserver tool
make	Build blogc-make tool

cb2bib

webengine	Use dev-qt/qtwebengine instead of dev-qt/qtwebkit

coolreader

wxwidgets	Use x11-libs/wxGTK instead of Qt5

crm114

mew	Add support for using the mewdecode mime decoder (app-emacs/mew)
mimencode	Add support for using the mimencode mime (net-mail/metamail)
normalizemime	Add support for using the normalizemime (mail-filter/normalizemime)

dbacl

interactive	Enable the interactive mailinspect ability

dblatex

inkscape	Use inkscape to convert SVG. Disable to use gnome-base/librsvg instead.

dictd

judy	Build Judy-based (dev-libs/judy) plugin implementing fast "exact" and especially "lev" strategies
minimal	Don't build server but dict client, dictzip and dictfmt only.

docbook-sgml-utils

jadetex	Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)

docbook-xsl-ns-stylesheets

ruby	Install the Ruby-based dbtoepub script; requires an interpreter compatible with app-eselect/eselect-ruby.

docbook-xsl-stylesheets

ruby	Install the Ruby-based dbtoepub script; requires an interpreter compatible with app-eselect/eselect-ruby.

ebook-tools

lit2epub	Install lit2epub script

editorconfig-core-c

cli	Install command line interface.

enchant

aspell	Adds support for app-text/aspell spell checker
hunspell	Adds support for app-text/hunspell spell checker

evince

dvi	Enable the built-in DVI viewer
nautilus	Enable property page extension in gnome-base/nautilus
postscript	Enable support for PostScript and Adobe Illustrator documents with app-text/libspectre
t1lib	Enable the Type-1 fonts for the built-in DVI viewer (media-libs/t1lib)
xps	Enable XPS viewer using app-text/libgxps

getxbook

ocr	Use app-text/tesseract for optical character recognition

ghostscript-gpl

unicode	Add support for unicode passwords via net-dns/libidn

glark

zip	Support for ZIP files using dev-ruby/rubyzip

groonga

abort	Enable query abortion
benchmark	Build benchmark programs
dynamic-malloc-change	Allow dynamic memory allocation change for testing
exact-alloc-count	Atomic counting for memory alloc count
fmalloc	Make memory allocation failed in specified condition for debug
futex	Use futex
jemalloc	Enable dev-libs/jemalloc for memory management
libevent	Enable dev-libs/libevent used for suggestion
mecab	Use app-text/mecab for morphological analysis
msgpack	Enable dev-libs/msgpack used for suggestion
nfkc	Use nfkc based utf8 normalization
sphinx	Enable document generation by app-misc/sphinx
uyield	Build for detecting race conditions
zeromq	Enable net-libs/zeromq used for suggestion
zstd	Utilize app-arch/zstd for Zstandard compression

gtranslator

gnome-dictionary	Enable plugin for dictionary lookups using app-dicts/gnome-dictionary.
gucharmap	Enable plugin for unicode symbols selection using gnome-extra/gucharmap.

hyperestraier

mecab	Enable app-text/mecab support for Estraier

kbibtex

webengine	Use dev-qt/qtwebengine for HTML previews
webkit	Use dev-qt/qtwebkit for HTML previews
zotero	Enable support for synchronisation with zotero.org web service

lcdf-typetools

kpathsea	Enable integration with kpathsea search library (TeX related)

libebook

tools	Build file conversion tools

libmwaw

tools	Build file conversion tools

libqxp

tools	Build file conversion tools

libstaroffice

tools	Build conversion tools
zlib	Enable support for compressed data

libwpd

tools	Build file conversion tools

libwps

tools	Build file conversion tools

mathtex

png	Generate png images by default instead of gif

mupdf

openssl	Use dev-libs/openssl crypto backend

pandoc

embed_data_files	Embed data files in binary for relocatable executable.
http-conduit	Enable downloading of resources over https.
https	Enable support for downloading of resources over https.
make-pandoc-man-pages	Build program to regenerate pandoc man pages from README.
network-uri	Get Network.URI from the network-uri package.
trypandoc	Build trypandoc cgi executable.
weigh-pandoc	Build weigh-pandoc to measure memory usage.

pastebinit

crypt	Install pbputs for gpg-encrypted pastes

pdfgrep

unac	Removing accents and ligatures before search

pelican

markdown	Markdown support

podofo

boost	Add support for boost
tools	Build and install commandline tools.

poppler

nss	Enable signatures handling with dev-libs/nss
utils	Install command-line PDF converters and various utilities.

qpdf

perl	Install fix-qdf tool (for reverting PDF edits) written in perl

qpdfview

fitz	Use experimental fitz rendering, provided by app-text/mupdf, instead of poppler
synctex	Add support for searching TeX sources

sdcv

darkterm	Improve readability of color output on terminals with dark background.

sgmltools-lite

jadetex	Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)

stardict

advertisement	Enable stardict advertisements plugin
cal	Enable calendar support using cal program
dictdotcn	Enable dict.cn network plugin (for Chinese language)
espeak	Enable text to speech synthesizer plugin using app-accessibility/espeak engine
flite	Enable text to speech synthesizer plugin using app-accessibility/flite engine
fortune	Enable plugin to read fortune messages using games-misc/fortune-mod. You may consider installing games-misc/fortune-mod-all to get all fortune messages.
gucharmap	Enable plugin for unicode symbols description using gnome-extra/gucharmap
htmlparse	Enable plugin to parse dictionaries with html content
info	Enable plugin to read info pages
man	Enable plugin to read manual pages
powerwordparse	Enable plugin to parse powerword dictionaries
pronounce	Install WyabdcRealPeopleTTS package (it is just many .wav files) to make StarDict pronounce English words
qqwry	Enable QQWry plugin, which provides information (in Chinese language) about geographical positions, owner, etc. for IP addresses
tools	Build and install dictionary management tools and converters from various dictionary formats
updateinfo	Enable plugin to check for stardict updates
wikiparse	Enable plugin to parse dictionaries in wikimedia format
wordnet	Enable wordnet plugin to find similar English words using lexical database
xdxfparse	Enable plugin to parse dictionaries in xdxf (XML Dictionary eXchange Format)
youdaodict	Enable youdao.com network plugin (for Chinese language)

sword

clucene	Use dev-cpp/clucene for lucene search support

tesseract

math	Enable support for recognition of equations.
opencl	Enable opencl support for speedup using GPU computation.
osd	Enable support orientation and script detection.
scrollview	Install viewer to debug recognition (ScrollView).
training	Install training applications to add support for new languages.
webp	Enable support for webp image format.

texlive

context	Add support for the ConTeXt format (dev-texlive/texlive-context)
detex	Add support for dev-tex/detex, a filter program that removes the LaTeX (or TeX) control sequences
dvi2tty	Add support for dev-tex/dvi2tty to preview dvi-files on text-only devices
epspdf	Add support for app-text/epspdf, a tool for converting [e]ps files to pdf
extra	Add support for extra TeXLive packages
games	Add typesetting support for games (chess, etc.) (dev-texlive/texlive-games)
graphics	Add support for several graphics packages (pgf, tikz,...)
humanities	Add LaTeX support for the humanities (dev-texlive/texlive-humanities)
jadetex	Add support for app-text/jadetex (for processing tex files produced by the TeX backend of Jade)
luatex	Add extra support for luatex
metapost	Add support for metapost: A tool for creating graphics in scalable PostScript
music	Add support for music typesetting (dev-texlive/texlive-music)
pdfannotextractor	Add dev-tex/pdfannotextractor support, for extracting annotations from PDF files
pstricks	Add pstricks packages (dev-texlive/texlive-pstricks)
publishers	Add support for publishers (dev-texlive/texlive-publishers)
science	Add typesetting support for natural and computer sciences (dev-texlive/texlive-mathscience)
tex4ht	Add support for dev-tex/tex4ht (for converting (La)TeX to (X)HTML, XML and OO.org)
texi2html	Add support for app-text/texi2html which converts texi files to HTML
xetex	Add support for XeTeX macros (dev-texlive/texlive-xetex)
xindy	Add support for app-text/xindy, a flexible indexing system

texlive-core

luajittex	Add support for LuaJitTeX: LuaTeX based on LuaJIT which is usually faster.
xetex	Add support for XeTeX: a TeX system with Unicode and modern font technologies.

wdiff

experimental	Build experimental utilities (mdiff, unify, wdiff2)

webgen

builder	Enable programmatic HTML/XML generation
highlight	Enable syntax highlighting for certain plugins
markdown	Markdown support

wklej

vim	Install the vim plugin allowing to paste through ':Wklej'.

writerperfect

abiword	Add support for abiword format using app-text/libabw
ebook	Add support for various ebook formats using app-text/libebook
freehand	Add support for freehand format using media-libs/libfreehand
gsf	Add support for structured files using gnome-extra/libgsf
keynote	Add support for keynote format using app-text/libetonyek
mspub	Add support to mspub format using app-text/libmspub
mwaw	Add support to mwaw formats using app-text/libmwaw
pagemaker	Add support to pagemaker formats using media-libs/libpagemaker
visio	Add support for visio format using media-libs/libvisio
wpd	Add support for wpd format using app-text/libwpd
wpg	Add support for wpg format using app-text/libwpg
wps	Add support for wps format using app-text/libwps

wv

tools	Install optional utilities considered deprecated in favor of using AbiWord.

xmlto

text	Support conversion from XML to plain text

zathura

magic	Use libmagic to determine mimetypes
synctex	Use libsynctex to get latex codeline from pdf

zathura-meta

cb	Install plug-in for ComicBook support

app-vim

gentoo-syntax

ignore-glep31	Remove GLEP 31 (UTF-8 file encodings) settings

youcompleteme

clang	Enable semantic support for C-family languages using sys-devel/clang

dev-ada

asis

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

aunit

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

aws

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

gnat_util

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build gnat_util shared library
static-pic	Build gnat_util static library with pic code

gnatcoll

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
projects	Adds support for projects
pygobject	Adds support for pygobject
shared	Build shared library
tools	Build associated tools

gnatcoll-bindings

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build shared library
static-pic	Build shared library

gnatcoll-core

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build shared library
static-pic	Build static library with pic code

gnatcoll-db

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
gnatcoll_db2ada	Build gnatcoll_db2ada
gnatinspect	Build gnatinspect
shared	Build shared library
sql	Build sql library
static-pic	Build shared library
xref	Build xref library

gnatmem

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

gprbuild

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

gtkada

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build gtkada as shared library

libadalang

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build shared library

libadalang-tools

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018

libgpr

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2018
shared	Build shared library
static-pic	Build static library with pic code

xmlada

gnat_2016	Compile with dev-lang/gnat-gpl-2016
gnat_2017	Compile with dev-lang/gnat-gpl-2017
gnat_2018	Compile with dev-lang/gnat-gpl-2017
shared	Build shared library
static-pic	Build static library with pic code

dev-cpp

eigen

c++11	Build using the C++11 standard
cuda	Build with cuda support

glog

gflags	Use dev-cpp/gflags for flag parsing
unwind	Use sys-libs/libunwind for stack unwinding instead of glibc/gcc (may be more reliable on x86_64)

libcmis

man	Build and install man pages.

libjson-rpc-cpp

http-client	Build support for HTTP client using net-misc/curl
http-server	Build support for HTTP server using net-libs/libmicrohttpd
redis-client	Build support for Redis client using dev-libs/hiredis
redis-server	Build support for Redis server using dev-libs/hiredis
stubgen	Build header stub code generator (needed for development and when pregenerated headers are not bundled)

sourcetrail

examples	Install example projects.

websocketpp

boost	Use dev-libs/boost instead of C++11

xsd

ace	Enable support for serializing to/from an ACE CDR stream

dev-db

aerospike-server-community

tools	Install extra tools

clickhouse

client	Build CLI client.
kafka	Enables support for kafka consumer.
mongodb	Enabled support for MongoDB-based dictionaries
server	Build server.
tools	Build various tools, like benchmark, copier, etc.
zookeeper	Enable support for clustering (based on Zookeeper).

cppdb

mysql_internal	Don't build a separate mysql loadable module but rather build it into the cppdb library itself
odbc_internal	Don't build a separate postgresql loadable module but rather build it into the cppdb library itself
postgres_internal	Don't build a separate odbc loadable module but rather build it into the cppdb library itself
sqlite_internal	Don't build a separate sqlite3 loadable module but rather build it into the cppdb library itself

etcd

server	Installs etcd daemon

firebird

server	Install the server components of Firebird, not just the client
xinetd	Install ClassicServer

maatkit

udf	Build the MySQL UDFs shipped with maatkit, requires non-minimal MySQL

mariadb

backup	Build mariadb-backup which supports SST and hot backup of InnoDB, Aria and MyISAM including compression and encryption
client-libs	Build the client libraries from the server package instead of the C Connector packages
extraengine	Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
galera	Enables galera replication
innodb-lz4	Enables lz4 compression methods for InnoDB/XtraDB
innodb-lzo	Enables lzo compression methods for InnoDB/XtraDB
innodb-snappy	Enables snappy compression methods for InnoDB/XtraDB using app-arch/snappy
jdbc	Enable the CONNECT engine to access foreign databases via JDBC
jemalloc	Use dev-libs/jemalloc for allocations.
latin1	Use LATIN1 encoding instead of UTF8
libressl	Enable SSL connections and crypto functions using dev-libs/libressl
mroonga	Add support for the Mroonga engine for interfacing with the Groonga text search
numa	Enable NUMA support using sys-process/numactl (NUMA kernel support is also required)
oqgraph	Add support for the Open Query GRAPH engine
pam	Enable the optional PAM authentication plugin for the server
profiling	Add support for statement profiling (requires USE=community).
rocksdb	Add support for RocksDB; a key/value, LSM database optimized for flash storage
server	Build the server program
sphinx	Add suport for the sphinx full-text search engine
sst-mariabackup	Add tools needed to support the mariabackup SST method
sst-rsync	Add tools needed to support the rsync SST method
sst-xtrabackup	Add tools needed to support the xtrabackup and xtrabackup-v2 SST methods
systemtap	Build support for profiling and tracing using dev-util/systemtap
test	Install upstream testsuites for end use.
tokudb	Add support for TokuDB storage engine
yassl	Enable SSL connections and crypto functions using the bundled yaSSL

mariadb-connector-c

mysqlcompat	Enable mysqlclient library symbolic links

mariadb-galera

client-libs	Build the client libraries from the server package instead of the C Connector packages
extraengine	Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jdbc	Enable the CONNECT engine to access foreign databases via JDBC
jemalloc	Use dev-libs/jemalloc for allocations.
latin1	Use LATIN1 encoding instead of UTF8
libressl	Enable SSL connections and crypto functions using dev-libs/libressl
numa	Enable NUMA support using sys-process/numactl (NUMA kernel support is also required)
oqgraph	Add support for the Open Query GRAPH engine
profiling	Add support for statement profiling (requires USE=community).
server	Build the server program
sphinx	Add suport for the sphinx full-text search engine
sst-rsync	Add tools needed to support the rsync SST method
sst-xtrabackup	Add tools needed to support the xtrabackup and xtrabackup-v2 SST methods
systemtap	Build support for profiling and tracing using dev-util/systemtap
test	Install upstream testsuites for end use.
tokudb	Add support for TokuDB storage engine
yassl	Enable SSL connections and crypto functions using the bundled yaSSL

mongodb

mms-agent	Install the MongoDB Monitoring Service agent
tools	Install the MongoDB tools (mongoimport, mongodump...) from app-admin/mongo-tools

mysql

client-libs	Build the client libraries from the server package instead of the C Connector packages (not recommended)
extraengine	Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc	Use dev-libs/jemalloc for allocations.
latin1	Use LATIN1 encoding instead of UTF8
libressl	Enable SSL connections and crypto functions using dev-libs/libressl
numa	Enable NUMA support using sys-process/numactl (NUMA kernel support is also required)
profiling	Add support for statement profiling (requires USE=community).
server	Build the server program
systemtap	Build support for profiling and tracing using dev-util/systemtap
test	Install upstream testsuites for end use.
yassl	Enable SSL connections and crypto functions using the bundled yaSSL

mysql-cluster

cluster	Add support for NDB clustering
community	Enables the community features from upstream.
embedded	Build embedded server (libmysqld)
extraengine	Add support for alternative storage engines (Archive, CSV, Blackhole, Federated(X), Partition)
jemalloc	Use dev-libs/jemalloc for allocations.
latin1	Use LATIN1 encoding instead of UTF8
libressl	Enable SSL connections and crypto functions using dev-libs/libressl
max-idx-128	Raise the max index per table limit from 64 to 128
minimal	Install client programs only, no server
numa	Enable NUMA support using sys-process/numactl (NUMA kernel support is also required)
openssl	Enable SSL connections and crypto functions using dev-libs/openssl
profiling	Add support for statement profiling (requires USE=community).
server	Build the server program
systemtap	Build support for profiling and tracing using dev-util/systemtap
test	Install upstream testsuites for end use.
yassl	Enable SSL connections and crypto functions using the bundled yaSSL

mysql-connector-c++

gcov	Build coverage support
legacy	Build the legacy 1.x API as well as the DevX API

oracle-instantclient

jdbc	Support for XA, Internationalization, and RowSet operations under JDBC
odbc	Libraries for enabling ODBC applications
sdk	Header files and an example makefile for developing Oracle applications
sqlplus	Libraries and executable for running SQL*Plus
tools	Workload Replay Client

percona-server

client-libs	Build the libmysqlclient libraries
jemalloc	Use dev-libs/jemalloc for allocations.
latin1	Use LATIN1 encoding instead of UTF8
libressl	Enable SSL connections and crypto functions using dev-libs/libressl
numa	Enable NUMA support using sys-process/numactl (NUMA kernel support is also required)
profiling	Add support for statement profiling (requires USE=community).
rocksdb	Add support for RocksDB; a key/value, LSM database optimized for flash storage
server	Build the server program
systemtap	Build support for profiling and tracing using dev-util/systemtap
test-suite	Install upstream testsuites for end use.
tokudb	Add support for TokuDB storage engine
tokudb-backup-plugin	Builds the TokuDB backup plugin
yassl	Enable SSL connections and crypto functions using the bundled yaSSL

pgadmin3

databasedesigner	Enable the Database Designer component

pgbouncer

c-ares	Use c-ares as the DNS backend instead of evdns (libevent).
udns	Use udns as the DNS backend instead of evdns (libevent). Supports IPv4 only.

pgpool2

memcached	Use memcached for query caching.

pgrouting

drivingdistance	Enable to calculate driving distance
html	Install HTML formatted documentation

phpmyadmin

setup	Installs the phpMyAdmin setup utility. Users who don't use the utility should disable this USE flag for security reasons as the setup tool was the target of various exploits in the past.

postgis

address-standardizer	Normalize US and CA postal addresses
gtk	Build graphical interface for shp2pgsql (shp2pgsql-gui)
mapbox	Add capability to transform geometry into Mapbox Vector Tile
topology	Build topology spatial types and functions

postgresql

llvm	Add support for llvm JIT engine
pg_legacytimestamp	Use double precision floating-point numbers instead of 64-bit integers for timestamp storage.
server	Disable to build and install the clients and libraries only.
uuid	Enable server side UUID generation (via dev-libs/ossp-uuid).

psqlodbc

iodbc	Use dev-db/libiodbc. Disable to use dev-db/unixODBC.

redis

jemalloc	Use dev-libs/jemalloc for allocations.
tcmalloc	Use tcmalloc from dev-util/google-perftools for allocations.

rethinkdb

jemalloc	Use dev-libs/jemalloc for allocations (default).
tcmalloc	Use tcmalloc from dev-util/google-perftools for allocations.

soci

boost	Enable boost support
empty	Build the sample backend called Empty

spatialite

geos	Add the sci-libs/geos library for exact topological tests
proj	Add the sci-libs/proj library for reprojection features
xls	Add the dev-libs/freexl library for xls import support

sqlite

secure-delete	Enable overwriting of deleted content with zeros by default (http://sqlite.org/pragma.html#pragma_secure_delete), causing some performance penalty
tools	Install additional tools

sqlitestudio

cli	Build CLI interface

tokumx

pax_kernel	Apply patch needed for hardened kernels

unixODBC

minimal	Disable bundled drivers and extra libraries (most users don't need these)
odbcmanual	Administrator, Internal Structure, Programmer and User documentation

dev-embedded

avrdude

ftdi	Enable support for USB FTDI chips via dev-embedded/libftdi

libftdi

tools	build ftdi_eeprom helper tool

openocd

cmsis-dap	Support for CMSIS-DAP compliant adapters
dummy	Build the dummy port driver
ftdi	Enable support for USB FTDI chips via dev-embedded/libftdi
jlink	Build the SEGGER J-Link driver
parport	Enable support for parport JTAG devices
verbose-io	Verbose IO and comm JTAG and USB messages

sdcc

boehm-gc	Enable Hans Boehm's garbage collector dev-libs/boehm-gc
device-lib	Enable built of devices libraries
ds390	Add support for Dallas DS390
ds400	Add support for Dallas DS400
gbz80	Add support for Gameboy gbz80
hc08	Add support for Freescale/Motorola HC08 based
mcs51	Add support for Intel mcs51
non-free	Enable non-free runtime library parts
packihx	Enable Intel HEX files pack utility
pic14	Add support for Microchip 14 bits PICs
pic16	Add support for Microchip 16 bits PICs
r2k	Add support for Rabbit 2000
r3ka	Add support for Rabbit 3000A
s08	Add support for Freescale/Motorola S08
sdbinutils	Enable SDCC library archive utilities sdar, sdranlib, sdnm
sdcdb	Enable SDCC source level debugger
sdcpp	Enable SDCC preprocessor based on GCC cpp
stm8	Add support for STMicroelectronics STM8
tlcs90	Add support for TLCS-90
ucsim	Enable software simulator for microcontrollers
z180	Add support for Zilog Z180
z80	Add support for Zilog Z80

urjtag

ftd2xx	Enable support for USB FTDI chips via dev-embedded/libftd2xx
ftdi	Enable support for USB FTDI chips via dev-embedded/libftdi

dev-games

aseprite

bundled-libs	Use the upstream provided bundled version of allegro 4.4.2
gtk3	Enable support for the experimental native GTK File Dialog
webp	Enable webp image format support

cegui

devil	Build the DevIL based ImageCodec module
freeimage	Build the FreeImage based ImageCodec module
irrlicht	Enable the Irrlicht renderer
ogre	Enable the OGRE renderer
tinyxml	Enable the Tiny XML parser module
xerces-c	Enable the Xerces-C++ XML parser module
zip	Enable the Minizip resource provider

guichan

allegro	Build the Allegro frontend

mygui

l10n_ru	Install some additional russian docs if 'doc' useflag enabled
ogre	Use the ogre render subsystem. (cannot combine with opengl)
opengl	Use the opengl render subsystem. (cannot combine with ogre)
plugins	Build MyGUI plugins
samples	Install MyGUI demos (needs ogre USE flag)
tools	Build the tools for development

ode

double-precision	more precise calculations at the expense of speed
gyroscopic	enable gyroscopic term (may cause instability)

ogre

boost	Enable boost support
cache	Enable GL state cache support
cg	NVIDIA toolkit plugin
double-precision	More precise calculations at the expense of speed
egl	Use egl instead of glx
experimental	Build experimental BETA components 'Bites' and 'HLMS'
freeimage	Support images via media-libs/freeimage
gl3plus	Build OpenGL 3+ RenderSystem (EXPERIMENTAL)
gles2	Build OpenGL ES 2.x RenderSystem
gles3	Enable OpenGL ES 3.x Features
ois	Pull in Object-oriented Input System library dev-games/ois for samples
poco	When USE=threads, use poco for threading
resman-pedantic	Resource Manager PEDANTIC : require an explicit resource group. Case sensitive lookup. Some demos might not work with this setting. (default: case-insensitive + sensitive lookup in all groups)
resman-strict	Resource Manager STRICT : search in default group if not specified otherwise. Case sensitive lookup. Some demos might not work with this setting. (default: case-insensitive + sensitive lookup in all groups)
tbb	When USE=threads, use tbb for threading
tools	Build and install helper tools
zip	Support zip archives

openscenegraph

asio	Enable support for dev-cpp/asio library
fox	Build examples using x11-libs/fox library
gdal	Enable support for sci-libs/gdal library
las	Enable support for geospatial data LAS LiDAR format using sci-geosciences/liblas
openinventor	Build OpenInventor plugin
osgapps	Build osg applications
sdl2	Use media-libs/libsdl2 additionally to media-libs/libsdl
xrandr	Enable support for the X xrandr extension

physfs

7zip	Enable 7zip/lzma archive support
grp	Enable Build Engine GRP archive support
hog	Enable Descent I/II HOG archive support
iso	Enable ISO9660 file support
mvl	Enable Descent I/II MVL archive support
qpak	Enable Quake I/II QPAK archive support
slb	Enable Independence War SLB archive support
vdf	Enable Gothic/Gothic II VDF archive support
wad	Enable Doom WAD archive support
zip	Enable ZIP archive support

simgear

dns	Enable DNS resolver via net-libs/udns
gdal	Enable alternative terrain engine based on pagedLOD via sci-libs/gdal
subversion	Enable terrasync scenery downloader

dev-haskell

abstract-deque

usecas	Enable the reference implementation to use hardware compare-and-swap.

aeson-pretty

lib-only	don't build 'aeson-pretty' executable.

ansi-terminal

example	Build the example application.

ansi-wl-pprint

example	Build the example application.

authenticate

network-uri	Get Network.URI from the network-uri package

bifunctors

semigroups	You can disable the use of the `semigroups` package using `-f-semigroups`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
tagged	You can disable the use of the `tagged` package using `-f-tagged`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

biosff

fclip	Build the fclip executable.
flower	Build the flower executable.
frecover	Build the frecover executable.

blaze-builder-enumerator

newbuilder	use bytestring-builder instead of blaze-builder-0.3

bytedump

executable	build executable file

bytes

test-doctests	Enable the doctest suite when using the enable-tests option for cabal.

c2hs

regression	run regression tests

cabal-install

network-uri	Get Network.URI from the network-uri package.
noprefs	Ignore 'preferred-versions' file from hackage's tarball.

certificate

executable	Build the executable

cgi

extensible-exceptions-in-base	Required to be enabled for >=dev-lang/ghc-7.
network-uri	Get Network.URI from the network-uri package.

chell

color-output	use colors in program output

citeproc-hs

bibutils	use Chris Putnam's app-text/bibutils
embed_data_files	Embed locale files into the library (needed for windows packaging)
hexpat	use dev-haskell/hexpat instead of dev-haskell/xml for XML parsing
network	use dev-haskell/network and dev-haskell/http to retrieve CSL file from URIs
small_base	Choose the new smaller, split-up base package.
unicode_collation	Use Haskell bindings to the dev-libs/icu

cmark

system-cmark	use app-text/cmark instead of bundled copy

cmdargs

quotation	Build quote module
testprog	Build the test program

comonad

containers	You can disable the use of the `containers` package using `-f-containers`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
contravariant	You can disable the use of the `contravariant` package using `-f-contravariant`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Contravariant`
distributive	You can disable the use of the `distributive` package using `-f-distributive`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Distributive`
test-doctests	Run the doctests test suite

conduit

nohandles	experimental code to use raw system calls in place of handles. Not recommended for general use

configfile

buildtests	Build the executable to run unit tests.

contravariant

safe	Get Safe guarantees rather than merely Trustworthy, but with worse constant factors.
semigroups	You can disable the use of the `semigroups` package using `-f-semigroups`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
statevar	You can disable the use of the `StateVar` package using `-f-StateVar`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
tagged	You can disable the use of the `tagged` package on older versons of GHC using `-f-tagged`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

cpu

executable	build 'cpuid' tool

crypto-api

all_cpolys	Build all the CMAC polynomes up to 10000 bits instead of just the usual ones

crypto-conduit

conduit11	Use conduit >= 1.1.

cryptohash

cryptoapi	Defines crypto-api instances

cryptonite

integer-gmp	Whether or not to use GMP for some functions
support_aesni	allow compilation with AESNI on system and architecture that supports it
support_blake2_sse	Use SSE optimized version of BLAKE2
support_deepseq	add deepseq instances for cryptographic types
support_pclmuldq	Allow compilation with pclmuldq on architecture that supports it
support_rdrand	allow compilation with AESNI on system and architecture that supports it

dav

network-uri	Get Network.URI from the network-uri package.

distributive

lib-werror	Compile with the ghc -Werror option

encoding

systemencoding	Provide the getSystemEncoding action to query the locale.

entropy

halvm	Build for the HaLVM.

filestore

maxcount	Make use of a recent (>= 2.3.0) Darcs feature which vastly improves the performance of 'latest'. You should disable this flag if you plan to use gitit with an older version of Darcs, or 'latest' will raise an error.

glib

closure_signals	Use the the GClosure-based signals implementation.

gtk

deprecated	Include definitions in this library that are considered obsolete.
fmode-binary	Set the default file translation mode for file I/O operations to _O_BINARY.
gio	Depend on GIO package, thereby enabling certain features.

gtk2hs-buildtools

closuresignals	Use the the GClosure-based signals implementation.

gtk3

fmode-binary	Set the default file translation mode for file I/O operations to _O_BINARY.
gio	Depend on GIO package, thereby enabling certain features.

hackage-security

use-network-uri	Get Network.URI from the network-uri package.

happstack-server

network-uri	Get Network.URI from the network-uri package
template_haskell	Description: Template Haskell is available on this system

hashed-storage

diff	Provide the Storage.Hashed.Diff module.
hpc	Compile with the profiling ghc flag -fhpc.

hashtables

bounds-checking	if on, use bounds-checking array accesses
portable	if on, use only pure Haskell code and no GHC extensions.
unsafe-tricks	turn on unsafe GHC tricks

haskeline

legacy-encoding	Use legacy iconv encoding for POSIX. This is only intended for testing.
libiconv	Explicitly link against the libiconv library.
terminfo	Use the terminfo package for POSIX consoles.

hdbc-odbc

buildstresstest	Build stress test

hdbc-sqlite3

buildtests	Build the executable to run unit tests
splitbase	Choose the new smaller, split-up package.

hexpat

bundled-expat	Use bundled expat instead of dev-libs/expat

highlighting-kate

executable	Build the Highlight executable.
pcre-light	Use the pcre-light library instead of regex-pcre-builtin.

hit

executable	Build the executable

hlint

gpl	Use GPL libraries, specifically hscolour.

hps

build-exec	Build the `hps-fractals' executable

hs3

network-uri	Get Network.URI from the network-uri package.

hslogger

buildtests	Build the executable to run unit tests.

hslua

apicheck	Compile Lua with -DLUA_USE_APICHECK..
system-lua	Use the system-wide lua instead of the bundled copy.

hsopenssl

fast-bignum	Enable fast moving of bignums between OpenSSL and GMP (GHC Only)

http

conduit10	Use version 1.0.x or below of the conduit package (for the test suite).
network-uri	Get Network.URI from the network-uri package.

http-api-data

use-text-show	Use text-show library for efficient ToHttpApiData implementations

http-client

network-uri	Get Network.URI from the network-uri package.

http-streams

network-uri	Get Network.URI from the network-uri package.

httpd-shed

buildexamples	Build example executables.
network-uri	Get Network.URI from the network-uri package.

hxt

network-uri	Get Network.URI from the network-uri package.

icalendar

network-uri	use network-uri package

json

generic	Add support for generic encoder (dev-haskell/syb)
mapdict	Encode Haskell maps as JSON dicts
parsec	Add support for parsing with Parsec
pretty	Add support for using pretty printing combinators

language-dot

executable	Build the `ppdot' executable

lens

benchmark-uniplate	Enable benchmarking against Neil Mitchell's uniplate library for comparative performance analysis. Defaults to being turned off to avoid the extra dependency.
dump-splices	Build and run the doctests test-suite.
inlining	Generate inline pragmas when using template-haskell. This defaults to enabled, but you can to shut it off to benchmark the relative performance impact, or as last ditch effort to address compile errors resulting from the myriad versions of template-haskell that all purport to be 2.8.
j	Attempt a parallel build with GHC 7.8.
lib-werror	Turn on ghc-options: -Werror
old-inline-pragmas	Some 7.6.1-rc1 users report their TH still uses old style inline pragmas. This lets them turn on inlining.
safe	Disallow unsafeCoerce
test-doctests	Build and run the doctests test-suite.
test-hlint	You can disable the hlint test suite with -f-test-hlint
test-hunit	You can disable the hunit test suite with -f-test-hunit
test-properties	Build the properties test if we're building tests
test-templates	Build the test templates if we're building tests
trustworthy	Assert that we are trustworthy when we can

lifted-async

monad-control-1	Use moand-control == 1.*

linear

template-haskell	You can disable the use of the `template-haskell` package using `-f-template-haskell`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

monad-control

instancest	If enabled this package will export MonadBaseControl instances for the lazy and strict ST monad. If disabled these instances are only exported when base >= 4.4. If enabled it is required that the transformer-base package exports MonadBase instances for ST. It will do this by default.

monad-logger

template_haskell	Enable Template Haskell support.

monad-par

chaselev	Use Chase-Lev Deques for higher-perf work-stealing.

nats

hashable	You can disable the use of the `hashable` package using USE=-hashable. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If set we will not supply an instance of `Hashable`.

network-data

small_base	Build the split-up base package.

pandoc-citeproc

bibutils	use Chris Putnam's app-text/bibutils
embed_data_files	Embed locale files into the library (needed for windows packaging)
hexpat	use dev-haskell/hexpat instead of dev-haskell/xml for XML parsing
network	use dev-haskell/network and dev-haskell/http to retrieve CSL file from URIs
small_base	Choose the new smaller, split-up base package.
test_citeproc	Build the test-citeproc program
unicode_collation	Use Haskell bindings to the dev-libs/icu

persistent

nooverlap	Use OverlappingInstances only for String. Only developers should use this.

persistent-sqlite

build-sanity-exe	Build a sanity check test executable.

pointed

comonad	optional instances
containers	optional instances
kan-extensions	optional instances
semigroupoids	optional instances
semigroups	optional instances
stm	optional instances
tagged	optional instances
transformers	optional instances
unordered-containers	optional instances

publicsuffixlist

create	export Network.PublicSuffixList.Create module
runtimelist	read suffix list from dist at startup instead of embedding list into library

quickcheck

template_haskell	Enable additional test modules requiring Template Haskell support.

recaptcha

network-uri	Get Network.URI from the network-uri package.

reflection

template-haskell	Enable template haskell.

rfc5051

mkunicodedata	build codes generator itself

sandi

with-conduit	Build with conduit

scientific

bytestring-builder	Provide the Data.ByteString.Builder.Scientific module (requires bytestring >= 0.10).

semigroupoid-extras

profunctors	You can disable the use of the `profunctors` package using `-f-profunctors`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

semigroupoids

comonad	You can disable the use of the `comonad` package using `-f-comonad`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Comonad`
containers	You can disable the use of the `containers` package using `-f-containers`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
contravariant	You can disable the use of the `contravariant` package using `-f-contravariant`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Contravariant`
distributive	You can disable the use of the `distributive` package using `-f-distributive`. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If disabled we will not supply instances of `Distributive`
tagged	You can disable the use of the `tagged` package using `-f-tagged`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

semigroups

binary	provide instances for binary package
bytestring	You can disable the use of the `bytestring` package using USE=-bytestring. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
containers	You can disable the use of the `containers` package using USE=-containers. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
deepseq	You can disable the use of the `deepseq` package using `-f-deepseq`. Disabing this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
hashable	You can disable the use of the `hashable` package using USE=-hashable. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users. If set we will not supply an instance of `Hashable`.
text	You can disable the use of the `text` package using USE=-text. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.
transformers	provide instances for transformers package.
unordered-containers	You can disable the use of the `unordered-containers` package using USE=-unordered-containers. Disabling this is an unsupported configuration, but it may be useful for accelerating builds in sandboxes for expert users.

sendfile

portable	Explicitly enable portable sendfile support (implemented in Haskell)

sha

exe	Build a sha1 and a sha384 executable similar to 'md5sum'.

shakespeare

test_coffee	Render tests through coffeescript render function.
test_export	Test export.
test_roy	Render tests through roy render function.

shakespeare-js

test_coffee	Test coffee.
test_export	Test export.
test_roy	Test roy.

shelly

lifted	run the tests against Shelly.Lifted

shuffle

network-uri	Get Network.URI from the network-uri package.

simple-sendfile

allow-bsd	Allow use of BSD sendfile (disable on GNU/kFreeBSD)

skein

big-endian	When manually selecting the endianness, use big-endian (default is little-endian)
force-endianness	Use a manually selected endian when compiling (see flag 'big-endian')
reference	Use the reference implementation instead of the optimized one

skylighting

executable	Build the skylighting executable.

snap-core

portable	No non-haskell unportable code.

snap-server

build-pong	Build a server that just returns "PONG"
openssl	enable https support using dev-haskell/hsopenssl
portable	no non-haskell unportable code.

tagsoup

download	Build with Download module.
testprog	Build the test program.

tasty

colors	Enable colorful output

tasty-quickcheck

old-quickcheck	Use Quick-Check < 2.7.

texmath

executable	Compile test executable.
network-uri	Get Network.URI from the network-uri package.

text

developer	operate in developer mode

thyme

bug-for-bug	bug-for-bug compatibility with time
lens	use the full lens package
show-internal	instance Show of internal representation

tls

compat	Accept SSLv2 compatible handshake.
network	Use the base network library.

transformers-base

orphaninstances	Build instances for orphan datatypes.

transformers-compat

three	Use transformers-0.3

unix-compat

old-time	build against old-time package

uuagc

with-loag	Use dev-haskell/minisat external SAT-solver to schedule all Linear Ordered AGs.

vector

boundschecks	Enable bounds checking
internalchecks	Enable internal consistency checks at the cost of a significant performance penalty
unsafechecks	Enable bounds checking in unsafe operations at the cost of a significant performance penalty

vector-algorithms

bench	Build a benchmarking program.
boundschecks	Enable bounds checking.
internalchecks	Enable internal consistency checks at the cost of a significant performance penalty.
properties	Enable quickcheck tests.
unsafechecks	Enable bounds checking in unsafe operations at the cost of a significant performance penalty.

void

safe	dissable effective but unsafe coersions

wai-app-static

print	print debug info.

warp

allow-sendfilefd	Allow use of sendfileFd (not available on GNU/kFreeBSD).
warp-debug	Add additional debuging information

x11

screensaver	whether to build XScreenSaver.

x509-store

executable	Build the executable

xss-sanitize

network-uri	Get Network.URI from the network-uri package.

yaml

no-examples	don't build the examples
no-exe	don't install the yaml2json executable
no-unicode	Don't enable unicode output. Instead, unicode characters will be escaped.
system-libyaml	Use system libyaml instead on generic one

yesod-auth

network-uri	Get Network.URI from the network-uri package

yesod-form

network-uri	Get Network.URI from the network-uri package

zip-archive

executable	Build the Zip executable.

zlib

non-blocking-ffi	Execute FFI calls in the context of haskell thread.

dev-java

ant

antlr	Enable ANTLR Ant tasks
bcel	Enable bcel (bytecode manipulation) Ant tasks
commonslogging	Enable commons-logging Ant tasks
commonsnet	Enable commons-net Ant tasks
jai	Enable JAI (Java Imaging) Ant task
javamail	Enable JavaMail Ant task
jdepend	Enable Jdepend Ant tasks
jmf	Enable JMF (Java Media Framework) Ant tasks
jsch	Disable Jsch (ssh, scp and related) Ant tasks
log4j	Enable Apache log4j Ant tasks
oro	Enable Apache Oro Ant tasks
regexp	Enable Apache Regexp Ant tasks
resolver	Enable Apache Resolver Ant tasks
testutil	Enable optional test util classes

commons-collections

test-framework	Install the test framework

commons-logging

avalon-framework	Add optional support for avalon-framework
avalon-logkit	Add optional support for avalon-logkit
log4j	Add optional support for log4j
servletapi	Add optional support for servletapi

ecj-gcj

native	Build a native binary along with the jar. Provides faster execution time, but needs about 1G memory and some patience to compile.

eclipse-ecj

ant	Support using ecj in Ant builds via dev-java/ant-eclipse-ecj

emma

launcher	Install /usr/bin/emma. Collides with sci-biology/emboss.

gcj-jdk

awt	Install AWT libraries, needed by some GUIs (not needed to build icedtea)

gnu-classpath

alsa	Build with ALSA javax.sound.midi provider
dssi	Build with DSSI javax.sound.midi provider
gconf	Build with GConf preferences backend
gjdoc	Build GJDoc, a documentation generator
gmp	Build with GMP backend for java.math.BigInteger
gtk	Build with Gtk+ AWT peers
xml	Build with native XML backend

icedtea

cacao	Use the CACAO virtual machine rather than HotSpot.
cups	Link against the CUPS library at compile time, rather than using it dynamically at runtime.
headless-awt	Don't install the X backend for AWT, needed by some GUIs (used to be X flag)
jamvm	Use the JamVM virtual machine rather than HotSpot.
jbootstrap	If possible, recompile the final IcedTea executables with itself.
kerberos	Link against Kerberos in order to obtain the cache location.
nsplugin	Enable browser plugin (NPPlugin), requires also the webstart flag to be enabled.
pax_kernel	Apply patch needed for pax enabled kernels.
pch	Build using pre-compiled headers.
sctp	Build the SCTP NIO channel implementation against lksctp
shenandoah	Include the Shenandoah ultra-low pause time garbage collector (-XX:+UseShenandoahGC) (arm64 and x86_64 only)
smartcard	Build the PCSC driver against pcsc-lite
sunec	Build the SunEC provider against system NSS
system-lcms	Build against the system LCMS installation rather than the in-tree copy.
webstart	Enable Web Start support (via NetX).
zero	Enable Zero assembler port (usually for non-HotSpot architectures)

icedtea-bin

headless-awt	Don't install the X backend for AWT, needed by some GUIs (used to be X flag)
webstart	Provide javaws command through symlink to icedtea-web

icedtea-web

javascript	Enable support for using proxy auto config (PAC) files.
nsplugin	Enable the browser plugin (NPPlugin).
tagsoup	Depend on dev-java/tagsoup which allows parsing malformed .jnlp files

itext

rtf	Build and provide libraries for rich text format
rups	Build and provide GUI for Reading/Updating PDF Syntax

jcs

admin	Enable JCS Admin servlets

jdbc-mysql

c3p0	Enable c3p0 support
log4j	Enable log4 support

jfreesvg

debug	Enable debugging during compilation.

jna

awt	Enables support for Java AWT
nio-buffers	Enables support for NIO buffers

log4j

javamail	Build the SMTPAppender
jms	Build the JMSAppender

logback

tomcat	Builds Apache Tomcat support

lucene

contrib	Include extra functionality from contrib/

miglayout

swt	Add support for the SWT toolkit.

oracle-jdk-bin

commercial	Install features requiring a commercial license for production use
gentoo-vm	Allow this JDK to be recognised by Gentoo (package manager, eselect, java-config, EXPERIMENTAL!)
gtk2	Enable GTK+ 2 support in JavaFX
gtk3	Enable GTK+ 3 support in JavaFX
headless-awt	Don't install the X backend for AWT, needed by some GUIs (used to be X flag)
javafx	Install JavaFX libraries
jce	Install Java Cryptographic Extension Unlimited Strength Jurisdiction Policy Files
source	Install JVM (and optionally JavaFX) sources
visualvm	Install VisualVM debugging tool

oracle-jre-bin

commercial	Install features requiring a commercial license for production use
gentoo-vm	Allow this JRE to be recognised by Gentoo (package manager, eselect, java-config, EXPERIMENTAL!)
gtk2	Enable GTK+ 2 support in JavaFX
gtk3	Enable GTK+ 3 support in JavaFX
headless-awt	Don't install the X backend for AWT, needed by some GUIs (used to be X flag)
javafx	Install JavaFX libraries
jce	Install Java Cryptographic Extension Unlimited Strength Jurisdiction Policy Files

proguard

ant	Ant task for using ProGuard in build.xml scripts

protobuf-java

nano	Enable code generator and runtime library designed specifically for resource-constrained systems, like Android

rxtx

lfd	Installs and uses LockFileServer daemon (lfd)

sbt

binary	Install from (Gentoo-compiled) binary instead of building from sources. Set this when you run out of memory during build.

dev-lang

bas

lr0	Use the LR0 parser instead of the recursive descending parser

crystal

blocking-stdio-hack	Keep STDIO file descriptors in blocking mode.
debug	Build each module as a separate object file. Speeds build up.
xml	Use the dev-libs/libxml2 library to enable Crystal xml module
yaml	Use the dev-libs/libyaml library to enable Crystal yaml module

erlang

compat-ethread	Enable compatibility with pre-pentium 4 CPUs in the ethread library.
dirty-schedulers	Enable dirty schedulers
hipe	HIgh Performance Erlang extension
kpoll	Enable kernel polling support

fpc

ide	Build and install the Free Pascal Compiler IDE

gdl

eigen	Build matrix manipulation with dev-cpp/eigen
grib	Add support for the meteorological GRIB format with sci-libs/grib_api
gshhs	Add support for projection adn continent maps with sci-geosciences/gshhs-data
hdf	Add support for the Hierarchical Data Format v.4
proj	Add support for sci-libs/proj (geographic projections)
udunits	Add support for manipulating units of physical quantities

ghc

binary	Install the binary version directly, rather than using it to build the source version.
ghcbootstrap	Internal: Bootstrap GHC from an existing GHC installation.
ghcmakebinary	Internal: Build binary friendly for redistribution.

gnat-gpl

awt	Useful only when building GCJ, this enables Abstract Window Toolkit (AWT) peer support on top of GTK+
cilk	Support the Cilk Plus language (C/C++ based languages for parallel programming)
fixed-point	Enable fixed-point arithmetic support for MIPS targets in gcc (Warning: significantly increases compile time!)
go	Build the GCC Go language frontend.
graphite	Add support for the framework for loop optimizations based on a polyhedral intermediate representation
libssp	Build SSP support into a dedicated library rather than use the code in the C library (DO NOT ENABLE THIS IF YOU DON'T KNOW WHAT IT DOES)
mpx	Enable support for Intel Memory Protection Extensions (MPX)
nopie	Disable PIE support (NOT FOR GENERAL USE)
nossp	Disable SSP support (NOT FOR GENERAL USE)
objc	Build support for the Objective C code language
objc++	Build support for the Objective C++ language
objc-gc	Build support for the Objective C code language Garbage Collector
pgo	Build GCC using Profile Guided Optimization (PGO)
regression-test	Run the testsuite and install the results (requires FEATURES=test)
sanitize	Build support for various sanitizer functions (ASAN/TSAN/etc...)
ssp	Build packages with stack smashing protector on by default
vtv	Build support for virtual table verification (a C++ hardening feature)

go

gccgo	Enable bootstrapping using gccgo

icon

iplsrc	install the icon programming library source

lazarus

minimal	Don't build extra packages from the bigide component

logtalk

fop	Support for generating pdf documentation using fop
xslt	Support for generating html documentation using xslt

lua

deprecated	make deprecated data structures/routines available

luajit

lua52compat	Enable some upwards-compatible features from Lua 5.2 that are unlikely to break existing code.

mercury

erlang	Support Mercury Erlang grade
trail	Support Mercury trail grades

mlton

binary	install a binary version
bootstrap-smlnj	Boostrap mlton with dev-lang/smlnj (takes a long time)
pax_kernel	Enable if the user plans to run the package under a pax enabled hardened kernel
stage3	After bootstrap building mlton with dev-lang/smlnj, rebuild mlton with the second stage build of mlton (recommended).

moarvm

asan	Enable clang's Address Sanitizer functionality. Expect longer compile time.
clang	Use clang compiler instead of GCC
jit	Enable Just-In-Time-Compiler. Has no effect except on AMD64 and Darwin.
optimize	Enable optimization via CFLAGS
ubsan	Enable clang's Undefined Behavior Sanitizer functionality. Expect longer compile time.

mono

pax_kernel	Enable if the user plans to run the package under a pax enabled hardened kernel
xen	Make mono generate code that is considerably faster on xen VMs but slightly slower on for normal systems.

nqp

clang	Toggle usage of the clang compiler in conjunction with MoarVM
moar	Build the MoarVM backend (experimental/broken)

ocaml

flambda	Enables the Flambda optimizer: A new intermediate representation (introduced in ocaml 4.03) in the depths of the compiler designed to allow for better inlining.
spacetime	Enables the Spacetime memory profiler. See https://caml.inria.fr/pub/docs/manual-ocaml/spacetime.html for more information.

orc

pax_kernel	Apply patch needed for pax enabled kernels.

perl

ithreads	Enable Perl threads, has some compatibility problems

php

argon2	Enable password hashing algorithm from app-crypt/argon2
cli	Enable CLI SAPI
coverage	Include gcov symbols for test coverage and lcov reports. Only useful for extension developers, and requires GCC.
embed	Enable embed SAPI
enchant	Add supports Enchant spelling library.
fileinfo	Add fileinfo extension support
filter	Add filter extension support
fpm	Enable the FastCGI Process Manager SAPI
gd	Adds support for gd (bundled with PHP)
hash	Enable the hash extension
intl	Enables the intl extension for extended internalization support
json	Enable JSON support
ldap-sasl	Add SASL support for the PHP LDAP extension
libmysqlclient	Use libmyslclient driver for mysql, mysqli, PDO_Mysql (not recommended)
lmdb	Enable support for dev-db/lmdb db backend
opcache	Enables built-in opcode cache, replacing pecl-apc et al.
pdo	Enable the bundled PDO extensions
phar	Enables the phar extension to provide phar archive support
phpdbg	Enable the PHP Debug Command Line SAPI (like gdb for php)
session-mm	Include dev-libs/mm support for session storage
sodium	Enable support for crypto through dev-libs/libsodium
tokyocabinet	Enable support for dev-db/tokyocabinet db backend
vpx	Enable webp support for GD in php-5.x
webp	Enable webp support for GD in php-7.x
xmlreader	Enable XMLReader support
xmlwriter	Enable XMLWriter support
xslt	Enable the XSL extension
zip	Enable ZIP file support
zip-encryption	Enable ZIP file encryption from dev-libs/libzip

polyml

portable	Build the portable interpreter version of Poly/ML instead of native

python

bluetooth	Build Bluetooth protocol support in socket module
threads	Enable threading support. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING)
wide-unicode	Enable wide Unicode implementation which uses 4-byte Unicode characters. Switching of this USE flag changes ABI of Python and requires reinstallation of many Python modules. (DON'T DISABLE THIS UNLESS YOU KNOW WHAT YOU'RE DOING)
wininst	Install Windows executables required to create an executable installer for MS Windows.

qu-prolog

pedro	Pedro subscription/notification communications system

rakudo

clang	Use Clang to compile the MoarVM backend
moar	Use the MoarVM as backend

ruby

jemalloc	Use dev-libs/jemalloc for memory allocation.
rdoc	Install dev-ruby/rdoc after installing Ruby.
readline	Use the sys-libs/readline library to provide the readline extension, used for instance by the irb tool. This flag is meaningful only if the libedit USE flag is disabled. If neither libedit nor readline USE flags are enabled, the readline extension will not be built (and irb will lose line editing functionality).
rubytests	Install ruby tests that can only be run after ruby is installed

rust

cargo	Install cargo component
extended	Build and install rls, rustfmt and cargo alongside the compiler and stdlib
jemalloc	Use dev-libs/jemalloc as the standard memory allocator
rls	Install rls component
rustfmt	Install rustfmt component
wasm	Build support for the wasm32-unknown-unknown target

rust-bin

cargo	Install cargo component
rustfmt	Install rustfmt component

scala

binary	Install from (Gentoo-compiled) binary instead of building from sources. Set this when you run out of memory during build.

smlnj

pax_kernel	Enable if the user plans to run the package under a pax enabled hardened kernel

spidermonkey

custom-optimization	Build with user-specified compiler optimizations (-Os, -O0, -O1, -O2, -O3) from CFLAGS (unsupported)
debug	Enable assertions to allow for easier debugging of programs that link to spidermonkey -- note this will often crash software on regular end-user systems
system-icu	Use the system-wide dev-libs/icu instead of bundled -- note, only takes effect when icu flag is enabled
threadsafe	Build a threadsafe version of spidermonkey

swi-prolog

archive	Use libarchive for extension packs
uuid	Use ossp-uuid for UUID pack
yaml	Use libyaml for YAML pack

swig

ccache	build ccache-swig(a fast compiler cache)

yap

R	Enable support for connecting R to Prolog

dev-libs

ace

ciao	Include Component Intergraced Ace ORB into the build of ace
tao	Include the ACE ORB (CORBA stuff) (called tao) into the build of ace

actor-framework

benchmarks	Due to the number of out-of-tree deps, these only get installed as docs
boost	Make use of Boost's ASIO functionality
cash	Build the C Actor Shell for introspection and debugging
debug	Raises log-level to DEBUG, enables runtime checks and address sanitizer
doc	Compiles and installs the documentation as PDF and HTML
examples	Installs the provided example source files
mem_management	Enables built-in memory management
nexus	Nexus is the central component for CAF's runtime inspection
opencl	Compiles against the provided opencl implementation
riac	Runtime inspection and configuration
static	Provides a static build
test	Builds the provided unit tests

antlr-c

debugger	Compiles debug info into the library

appstream

apt	Enables Debians APT support

appstream-glib

stemmer	Add word stemming via dev-libs/snowball-stemmer.

apr

older-kernels-compatibility	Enable binary compatibility with older kernels
urandom	Use /dev/urandom instead of /dev/random

apr-util

libressl	Use dev-libs/libressl instead of dev-libs/openssl for 'openssl' USE flag
nss	Install apr_crypto_nss module
openssl	Install apr_crypto_openssl module

atcore

gui	Build test GUI

aws-sdk-cpp

aws_targets_AWSMigrationHub	SDK Support for AWS AWSMigrationHub
aws_targets_access-management	SDK Support for AWS access-management
aws_targets_acm	SDK Support for AWS acm
aws_targets_acm-pca	SDK Support for AWS acm-pca
aws_targets_alexaforbusiness	SDK Support for AWS alexaforbusiness
aws_targets_apigateway	SDK Support for AWS apigateway
aws_targets_application-autoscaling	SDK Support for AWS application-autoscaling
aws_targets_appstream	SDK Support for AWS appstream
aws_targets_appsync	SDK Support for AWS appsync
aws_targets_athena	SDK Support for AWS athena
aws_targets_autoscaling	SDK Support for AWS autoscaling
aws_targets_autoscaling-plans	SDK Support for AWS autoscaling-plans
aws_targets_batch	SDK Support for AWS batch
aws_targets_budgets	SDK Support for AWS budgets
aws_targets_ce	SDK Support for AWS ce
aws_targets_cloud9	SDK Support for AWS cloud9
aws_targets_clouddirectory	SDK Support for AWS clouddirectory
aws_targets_cloudformation	SDK Support for AWS cloudformation
aws_targets_cloudfront	SDK Support for AWS cloudfront
aws_targets_cloudhsm	SDK Support for AWS cloudhsm
aws_targets_cloudhsmv2	SDK Support for AWS cloudhsmv2
aws_targets_cloudsearch	SDK Support for AWS cloudsearch
aws_targets_cloudsearchdomain	SDK Support for AWS cloudsearchdomain
aws_targets_cloudtrail	SDK Support for AWS cloudtrail
aws_targets_codebuild	SDK Support for AWS codebuild
aws_targets_codecommit	SDK Support for AWS codecommit
aws_targets_codedeploy	SDK Support for AWS codedeploy
aws_targets_codepipeline	SDK Support for AWS codepipeline
aws_targets_codestar	SDK Support for AWS codestar
aws_targets_cognito-identity	SDK Support for AWS cognito-identity
aws_targets_cognito-idp	SDK Support for AWS cognito-idp
aws_targets_cognito-sync	SDK Support for AWS cognito-sync
aws_targets_comprehend	SDK Support for AWS comprehend
aws_targets_config	SDK Support for AWS config
aws_targets_connect	SDK Support for AWS connect
aws_targets_core	SDK Support for AWS core
aws_targets_cur	SDK Support for AWS cur
aws_targets_datapipeline	SDK Support for AWS datapipeline
aws_targets_dax	SDK Support for AWS dax
aws_targets_devicefarm	SDK Support for AWS devicefarm
aws_targets_directconnect	SDK Support for AWS directconnect
aws_targets_discovery	SDK Support for AWS discovery
aws_targets_dms	SDK Support for AWS dms
aws_targets_ds	SDK Support for AWS ds
aws_targets_dynamodb	SDK Support for AWS dynamodb
aws_targets_dynamodbstreams	SDK Support for AWS dynamodbstreams
aws_targets_ec2	SDK Support for AWS ec2
aws_targets_ecr	SDK Support for AWS ecr
aws_targets_ecs	SDK Support for AWS ecs
aws_targets_eks	SDK Support for AWS eks
aws_targets_elasticache	SDK Support for AWS elasticache
aws_targets_elasticbeanstalk	SDK Support for AWS elasticbeanstalk
aws_targets_elasticfilesystem	SDK Support for AWS elasticfilesystem
aws_targets_elasticloadbalancing	SDK Support for AWS elasticloadbalancing
aws_targets_elasticloadbalancingv2	SDK Support for AWS elasticloadbalancingv2
aws_targets_elasticmapreduce	SDK Support for AWS elasticmapreduce
aws_targets_elastictranscoder	SDK Support for AWS elastictranscoder
aws_targets_email	SDK Support for AWS email
aws_targets_es	SDK Support for AWS es
aws_targets_events	SDK Support for AWS events
aws_targets_firehose	SDK Support for AWS firehose
aws_targets_fms	SDK Support for AWS fms
aws_targets_gamelift	SDK Support for AWS gamelift
aws_targets_glacier	SDK Support for AWS glacier
aws_targets_glue	SDK Support for AWS glue
aws_targets_greengrass	SDK Support for AWS greengrass
aws_targets_guardduty	SDK Support for AWS guardduty
aws_targets_health	SDK Support for AWS health
aws_targets_iam	SDK Support for AWS iam
aws_targets_identity-management	SDK Support for AWS identity-management
aws_targets_importexport	SDK Support for AWS importexport
aws_targets_inspector	SDK Support for AWS inspector
aws_targets_iot	SDK Support for AWS iot
aws_targets_iot-data	SDK Support for AWS iot-data
aws_targets_iot-jobs-data	SDK Support for AWS iot-jobs-data
aws_targets_iot1click-devices	SDK Support for AWS iot1click-devices
aws_targets_iot1click-projects	SDK Support for AWS iot1click-projects
aws_targets_iotanalytics	SDK Support for AWS iotanalytics
aws_targets_kinesis	SDK Support for AWS kinesis
aws_targets_kinesis-video-archived-media	SDK Support for AWS kinesis-video-archived-media
aws_targets_kinesis-video-media	SDK Support for AWS kinesis-video-media
aws_targets_kinesisanalytics	SDK Support for AWS kinesisanalytics
aws_targets_kinesisvideo	SDK Support for AWS kinesisvideo
aws_targets_kms	SDK Support for AWS kms
aws_targets_lambda	SDK Support for AWS lambda
aws_targets_lex	SDK Support for AWS lex
aws_targets_lex-models	SDK Support for AWS lex-models
aws_targets_lightsail	SDK Support for AWS lightsail
aws_targets_logs	SDK Support for AWS logs
aws_targets_machinelearning	SDK Support for AWS machinelearning
aws_targets_macie	SDK Support for AWS macie
aws_targets_marketplace-entitlement	SDK Support for AWS marketplace-entitlement
aws_targets_marketplacecommerceanalytics	SDK Support for AWS marketplacecommerceanalytics
aws_targets_mediaconvert	SDK Support for AWS mediaconvert
aws_targets_medialive	SDK Support for AWS medialive
aws_targets_mediapackage	SDK Support for AWS mediapackage
aws_targets_mediastore	SDK Support for AWS mediastore
aws_targets_mediastore-data	SDK Support for AWS mediastore-data
aws_targets_mediatailor	SDK Support for AWS mediatailor
aws_targets_meteringmarketplace	SDK Support for AWS meteringmarketplace
aws_targets_mobile	SDK Support for AWS mobile
aws_targets_mobileanalytics	SDK Support for AWS mobileanalytics
aws_targets_monitoring	SDK Support for AWS monitoring
aws_targets_mq	SDK Support for AWS mq
aws_targets_mturk-requester	SDK Support for AWS mturk-requester
aws_targets_neptune	SDK Support for AWS neptune
aws_targets_opsworks	SDK Support for AWS opsworks
aws_targets_opsworkscm	SDK Support for AWS opsworkscm
aws_targets_organizations	SDK Support for AWS organizations
aws_targets_pi	SDK Support for AWS pi
aws_targets_pinpoint	SDK Support for AWS pinpoint
aws_targets_polly	SDK Support for AWS polly
aws_targets_pricing	SDK Support for AWS pricing
aws_targets_queues	SDK Support for AWS queues
aws_targets_rds	SDK Support for AWS rds
aws_targets_redshift	SDK Support for AWS redshift
aws_targets_rekognition	SDK Support for AWS rekognition
aws_targets_resource-groups	SDK Support for AWS resource-groups
aws_targets_resourcegroupstaggingapi	SDK Support for AWS resourcegroupstaggingapi
aws_targets_route53	SDK Support for AWS route53
aws_targets_route53domains	SDK Support for AWS route53domains
aws_targets_s3	SDK Support for AWS s3
aws_targets_s3-encryption	SDK Support for AWS s3-encryption
aws_targets_sagemaker	SDK Support for AWS sagemaker
aws_targets_sagemaker-runtime	SDK Support for AWS sagemaker-runtime
aws_targets_sdb	SDK Support for AWS sdb
aws_targets_secretsmanager	SDK Support for AWS secretsmanager
aws_targets_serverlessrepo	SDK Support for AWS serverlessrepo
aws_targets_servicecatalog	SDK Support for AWS servicecatalog
aws_targets_servicediscovery	SDK Support for AWS servicediscovery
aws_targets_shield	SDK Support for AWS shield
aws_targets_sms	SDK Support for AWS sms
aws_targets_snowball	SDK Support for AWS snowball
aws_targets_sns	SDK Support for AWS sns
aws_targets_sqs	SDK Support for AWS sqs
aws_targets_ssm	SDK Support for AWS ssm
aws_targets_states	SDK Support for AWS states
aws_targets_storagegateway	SDK Support for AWS storagegateway
aws_targets_sts	SDK Support for AWS sts
aws_targets_support	SDK Support for AWS support
aws_targets_swf	SDK Support for AWS swf
aws_targets_text-to-speech	SDK Support for AWS text-to-speech
aws_targets_transcribe	SDK Support for AWS transcribe
aws_targets_transfer	SDK Support for AWS transfer
aws_targets_translate	SDK Support for AWS translate
aws_targets_waf	SDK Support for AWS waf
aws_targets_waf-regional	SDK Support for AWS waf-regional
aws_targets_workdocs	SDK Support for AWS workdocs
aws_targets_workmail	SDK Support for AWS workmail
aws_targets_workspaces	SDK Support for AWS workspaces
aws_targets_xray	SDK Support for AWS xray

beignet

ocl-icd	Enable compatibility with the dev-libs/ocl-icd OpenCL ICD loader
ocl20	Enable experimental OpenCL 2.0 support on Skylake and newer architectures

bitset

jemalloc	Use dev-libs/jemalloc for allocations
tcmalloc	Use tcmalloc from dev-util/google-perftools for allocations

blitz

boost	Enable usage of boost::serialization

boost

context	Build and install the Boost.Context (and Boost.Fiber) library and all other Boost libraries that depend on it
debug	Build and install only the debug version of the Boost libraries. Only enable this flag if you're developing against boost.
doc	Install the full API documentation documentation. This takes over 200MB of extra disk space.
nls	Build libboost_locale. This library requires compatible C library interfaces, which might not be provided by uClibc or other embedded libraries.
threads	Build multi-thread-compatible libraries instead of single-threaded only.
tools	Build and install the boost tools (bcp, quickbook, inspect, wave)

botan

boost	use dev-libs/boost

c-blosc

lz4	Enable lz4 compression
snappy	Enable snappy compression
zstd	Enable zstd compression

check

subunit	Enable support for the subunit unit test protocol

crypto++

asm	Support assembly hand optimized crypto functions (i.e. faster run time)

cyberjack

fox	Enable installation of x11-libs/fox based fxcyberjack program

cyrus-sasl

authdaemond	Add Courier-IMAP authdaemond unix socket support (net-mail/courier-imap, mail-mta/courier)
ldapdb	Enable ldapdb plugin
openldap	Add ldap support for saslauthd
sample	Enable sample client and server
srp	Enable SRP authentication
urandom	Use /dev/urandom instead of /dev/random

dbus-c++

ecore	Use Ecore integration
glib	Use glib integration

eekboard

libcanberra	Enable support for media-libs/libcanberra
xtest	Enable support for x11-libs/libXtst

efl

bmp	Enable WBMP image loader
dds	Enable DDS image loader
drm	Enable DRM engine
eet	Enable Eet image loader
egl	Enable EGL rendering
fribidi	Enable bidirectional text support
gles	Enable the OpenGL ES GL implementation
glib	Enable dev-libs/glib support
harfbuzz	Enable complex text shaping and layout support
hyphen	Enable text hyphenation support
ibus	Enable Intelligent Input Bus
ico	Enable Ico image loader
ivi	Enable ivi-shell support
libuv	Enable dev-libs/libuv support
luajit	USE dev-lang/luajit instead of dev-lang/lua
physics	Enable Bullet physics effects and support
pixman	Enable PixMan for software rendering
ppm	Enable PMAPS image loader
psd	Enable PSD image loader
scim	Enable Smart Common Input Method
system-lz4	Use system liblz4 instead of bundled one
tga	Enable Tga image loader
tslib	Enable x11-libs/tslib for touchscreen events
unwind	Enable debug support via sys-libs/libunwind
valgrind	Enable usage of dev-util/valgrind in debug
vlc	Enable media-video/vlc support
webp	Enable WebP image loader
xcf	Enable XCF image loader
xim	Enable X Input Method
xpresent	Enable x11-libs/libXpresent support

elfutils

lzma	Support automatic decompression of LZMA-compressed files and kernel images
threads	Build the libraries with thread safe support
utils	Install command-line utilities (all the eu-* programs)

ell

glib	Enable dev-libs/glib support

fcgi

html	Install HTML documentation

folks

telepathy	Load contacts from the Telepathy framework
tracker	Load contacts from app-misc/tracker index
utils	Build the folks-inspect utility

fstrm

utils	Build fstrm utility programs

gecode

gist	Enable Gist, the Gecode Interactive Search Tool
gmp	Enable trigonometric and transcendental float constraints

gf2x

bindist	Disable automatic fine-tuning to local processor features like pclmul or sse2.
custom-tune	Extra long compile time for tuning hardware specific low-level routines
fft	Build an FFT API for multiplication of 2 polynomials over GF(2)

glib

dbus	Enable dependencies required by glib libraries using dbus service to manage settings saving
mime	Pull in shared MIME database that many glib-based applications require at runtime to detect or open files. Warning: do not disable this flag unless installing on a headless server.
systemtap	Build support for profiling and tracing using dev-util/systemtap
utils	Install gtester-report utility to generate test report files for your software; build gresource utility with ELF support.

gmime

smime	Enable experimental S/MIME support

gmp

asm	Enable use of hand optimized assembly routines (faster execution)
pgo	After building gmp, run some tests against to produce faster libraries -- this option will double the compile time

gobject-introspection

doctool	Install g-ir-doc-tool for generating documentation from introspected data

granite

demo	Build the Granite demo application (to present all available UI features provided by the library)

hidapi

fox	Build a x11-libs/fox GUI

input-pad

eekboard	Enable support for dev-libs/eekboard
xtest	Enable support for x11-libs/libXtst

jemalloc

hugepages	Enable transparent huge page support
lazy-lock	Enable lazy locking (only lock when multi-threaded)
stats	Enable statistics calculation/reporting
xmalloc	Add support for xmalloc (abort-on-out-of-memory)

kreport

marble	Enable displaying of maps using kde-apps/marble
scripting	Support Qml scripting using dev-qt/qtdeclarative

leveldb

snappy	support the snappy compression library

libbase58

tools	Build command line base58 tool

libcdio

minimal	Only build the libcdio library and little more, just to be used to link against from multimedia players. With this USE flag enabled, none of the command-line utilities are built, nor is the CDDA library.

libcec

cubox	Enable support for enable support for the TDA995x
exynos	Enable support for Exynos chipsets
raspberry-pi	Enable support for the Raspberry Pi
xrandr	Enable detection of active HDMI using xrandr extensions

libcgroup

daemon	Install the configuration tools and init/config files.
tools	Install the cgroup rules processing daemon and init/config files.

libclsync

extra-debug	Enable extra debugging. This will hurt performance badly. Be ready for tons of output.
extra-hardened	Enable extra security checks. This may hurt performance.

libdbusmenu

gtk	Enable support for GTK+2
gtk3	Enable support for GTK+3

libdivecomputer

tools	Install tools that can be used to test the library.

libdynd

cuda	Enable NVIDIA CUDA toolkit support
mkl	Enable a plugin for Intel Math Kernel Library sci-libs/mkl

libevent

debug	Support runtime debug mode and malloc hooks (for programmers)

libffi

pax_kernel	Use PaX emulated trampolines, for we can't use PROT_EXEC

libflatarray

cuda	Enables plugins for NVIDIA GPUs (e.g. CUDAAllocator)

libgcrypt

o-flag-munging	Enable O-flag mangling during build

libgdata

gnome-online-accounts	Enable net-libs/gnome-online-accounts support

libgit2

curl	Use net-misc/curl for HTTP support (otherwise, limited built-in implementation will be used)
gssapi	Enable GSSAPI support for SPNEGO auth
ssh	Enable SSH transport support
trace	Enable tracing support

libgit2-glib

ssh	Enable SSH transport support

libgpg-error

common-lisp	Install common-lisp files

libgpiod

tools	Build some useful gpio tools that use libgpiod.

libgpuarray

cuda	Enable NVIDIA CUDA toolkit support
opencl	Enable OpenCL support

libgweather

glade	Installs catalog files for dev-util/glade

libisoburn

external-filters	Allow the use of external processes as file content filters (Note: this is a potential security risk)
external-filters-setuid	Also allow the use of external setuid processes as file content filters (Note: this is a potential security risk)
frontend-optional	Use dev-tcltk/bwidget which is not strictly required for the frontend
launch-frontend	Enable the tcl gui for xorriso
launch-frontend-setuid	Enable the tcl gui for xorriso under setuid

libisofs

verbose-debug	Enable verbose debug messages

liblogging

rfc3195	Enables RFC 3195 protocol (aka syslog-reliable) support. If you don't know what this is, you don't need it!
stdlog	Enables liblogging's core component (think of it as a the next version of the syslog(3) API).

libmail

apop	Enables the APOP authentication method

libmateweather

gtk3	Build with GTK+3 instead of GTK+2

libmemcached

hsieh	Use Hsieh hash algorithm.
libevent	Use the libevent event loop interface.
sasl	Use sasl auth for communications.

libmspack

utils	Enables building cabrip, chmextract, msexpand and oabextract

libnfc

pcsc-lite	Enable NFC drivers that require pcsc-lite

libnl

doc	Install development documentation
python	Install experimental dev-lang/python bindings
utils	Install command line interface utils

liborcus

spreadsheet-model	Enable the spreadsheet model implementation
tools	Build various low-level parsers

libowfat

diet	Compile against dev-libs/dietlibc

libp11

doc	Generate and install API documentation for the package.

libpcre

bzip2	Add support for pcregrep command to search within bzip2-compressed files (via app-arch/bzip2).
pcre16	Build PCRE library for 16 bit characters (e.g. UTF-16).
pcre32	Build PCRE library for 32 bit characters (e.g. UTF-32).
readline	Add support for command line editing to pcretest, through sys-libs/readline.
recursion-limit	Limit match recursion to 8192; if disabled, the default limit is used, which is the same as the match limit.
zlib	Add support for pcregrep command to search within gzip-compressed files (via sys-libs/zlib).

libpcre2

bzip2	Add support for pcregrep command to search within bzip2-compressed files (via app-arch/bzip2).
pcre16	Build PCRE library for 16 bit characters (e.g. UTF-16).
pcre32	Build PCRE library for 32 bit characters (e.g. UTF-32).
readline	Add support for command line editing to pcretest, through sys-libs/readline.
recursion-limit	Limit match recursion to 8192; if disabled, the default limit is used, which is the same as the match limit.
zlib	Add support for pcregrep command to search within gzip-compressed files (via sys-libs/zlib).

libpeas

glade	Install the glade catalog
python	Build support for loading dev-lang/python plugins

librdkafka

lz4	Enable support for Kafka's LZ4 compression based on KIP-57 (uses app-arch/lz4)

librelp

gnutls	Use GnuTLS
libressl	Use LibreSSL
openssl	Use OpenSSL

libressl

asm	Enables assembly

libsecp256k1

asm	Enable x86_64 assembly optimisation
ecdh	Enable ECDH shared secret computation
endomorphism	Enable endomorphism
experimental	Allow experimental USE flags
recovery	Enable ECDSA pubkey recovery module
schnorr	Enable Schnorr signature module
test_openssl	Enable OpenSSL comparison tests

libslz

tools	Install additional tools (zenc, zdec)

libsodium

asm	Enables assembly implementations
urandom	Use /dev/urandom instead of /dev/random

libsolv

rpm	Enable support for RPM files

libspt

libtirpc	Build against net-libs/libtirpc for RPC support

libsqlora8

orathreads	Use Oracle threads

libtasn1

valgrind	Enable usage of dev-util/valgrind in debug

libtermkey

demos	Install demos, which pulls in dev-libs/glib

libucl

regex	Enable regex checking for schema
signatures	Enable signatures check
urlfetch	Enable URLs fetch
utils	Install the chargen and objdump utilities

libunibreak

doc	Install html API documentation.
man	Generate man pages with doxygen.

libverto

glib	Support event loops using dev-libs/glib
libev	Support event loops using dev-libs/libev
libevent	Support event loops using dev-libs/libevent
tevent	Support event loops using sys-libs/tevent

libzia

ftdi	Enable support for FTDI USB chips

link-grammar

aspell	Adds support for app-text/aspell spell checker
hunspell	Adds support for app-text/hunspell spell checker

log4cplus

iconv	Use inconv for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation
working-c-locale	Use the C99 locale facilities for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation
working-locale	Use C++'s std::locale for wchar_t <-> char conversions. See also log4cplus's unicode.txt documentation

log4cxx

smtp	Offer SMTP support via net-libs/libesmtp

m17n-lib

X	Build the Graphical User Interface API and utilities
anthy	Enable support for app-i18n/anthy input method
athena	Enable the MIT Athena widget set (x11-libs/libXaw)
gd	Build API and utilities based on media-libs/gd. This flag is only meaningful if the X USE flag is also enabled
libotf	Use dev-libs/libotf to handle OpenType fonts
libxml2	Use dev-libs/libxml2 to parse XML

nss

cacert	Include root/class3 certs from CAcert (http://www.cacert.org/)
nss-pem	Add support for libnsspem
utils	Install utilities included with the library

onigmo

combination-explosion-check	enable combination explosion check
crnl-as-line-terminator	enable CR+NL as line terminator

oniguruma

combination-explosion-check	enable combination explosion check
crnl-as-line-terminator	enable CR+NL as line terminator

opencryptoki

tpm	Enable support for Trusted Platform Module (TPM) using app-crypt/trousers

openct

debug	Add debug output to the driver library for pcsc-lite.
pcsc-lite	Build a driver library for sys-apps/pcsc-lite, providing PC/SC API access to devices supported by OpenCT.
udev	Install rules for sys-fs/udev to auto-start openct.

openobex

irda	Enable IrDA support

opensc

ctapi	Use CT-API for accessing Smartcard hardware
notify	Enable notifications
openct	Use dev-libs/openct (and CT-API) for accessing Smartcard hardware
pcsc-lite	Use sys-apps/pcsc-lite (and PC/SC API) for accessing Smartcard hardware
secure-messaging	Enable secure messaging

openssl

asm	Support assembly hand optimized crypto functions (i.e. faster run time)
bindist	Disable/Restrict EC algorithms (as they seem to be patented) -- note: changes the ABI
rfc3779	Enable support for RFC 3779 (X.509 Extensions for IP Addresses and AS Identifiers)
sslv2	Support for the old/insecure SSLv2 protocol -- note: not required for TLS/https
sslv3	Support for the old/insecure SSLv3 protocol -- note: not required for TLS/https
tls-heartbeat	Enable the Heartbeat Extension in TLS and DTLS

pkcs11-helper

nss	Enable NSS crypto engine

poco

7z	Add Support for the 7z archive format
apache	Enable support to write Apache modules using POCO
cppparser	Build and install a minimal C++ parser
crypto	Encryption and digital signing classes
data	Database abstraction layer to easily send/retrieve data to/from various databases
file2pagecompiler	Utility to convert ordinary files to Page Compiler source files
json	Add JSON support
mongodb	Add dev-db/mongodb support
net	Classes to write network clients & servers
pagecompiler	Simple compiler translating HTML pages containing embedded C++ code into HTTPRequestHandler classes
pocodoc	POCO documentation generator
util	Several utility classes (like logger, timer, config file parser)
zip	Add support for the zip & gz archive formats

ppl

lpsol	Build the ppl_lpsol linear programming problem solver

serdisplib

tools	Build optional tools.

softhsm

migration-tool	Build db migration tool

starpu

cuda	Enable NVIDIA CUDA toolkit support
gcc-plugin	Enable GCC extension plugin (experimental)
opencl	Enable OpenCL support

sway

gdk-pixbuf	Enable additional image format support via the x11-libs/gdk-pixbuf library.
swaybar	Build 'swaybar': sway's status bar component.
swaybg	Build 'swaybg': allows to set a desktop background image.
swaygrab	Build 'swaygrab': allows taking screenshots or screencasts.
swaylock	Build 'swaylock': sway's screen locker.
swaymsg	Build 'swaymsg': tool for communicating with a running sway instance.
tray	Enable support for StatusNotifierItem tray specification.
wallpapers	Install sway's default wallpaper image.

tinyxml

stl	Compile with TIXML_USE_STL support

tntnet

server	Enable tntnet server daemon

totem-pl-parser

archive	Enables support for accessing media files in archives transparently via app-arch/libarchive
quvi	Use media-libs/libquvi for parsing video links

tvision

gpm	Support text mode mouse through sys-libs/gpm

ucommon

socks	Build with socks proxy support

userspace-rcu

regression-test	Run regression tests (requires FEATURES=test)

ustr

ustr-import	Install ustr-import developer program and source code for bundling.

weston

colord	Allow setting color managment
drm	Enable drm compositor support
editor	Install wayland-editor example application
fbdev	Enable fbdev compositor support
gles2	Use GLESv2 cairo instead of full GL
headless	Headless backend and a noop renderer, mainly for testing purposes
ivi	Enable the IVI shell
launch	Install weston-launch utility
rdp	Enable Remote Desktop Protocol compositor support
resize-optimization	Increase performance, allocate more RAM. Recommended to disable on Raspberry Pi
screen-sharing	Enable screen-sharing through RDP
unwind	Enable libunwind usage for backtraces
wayland-compositor	Enable Wayland compositor support
webp	Add support for the WebP image format
xwayland	Enable ability support native X11 applications

wlc

X	Enable X11 backend.
systemd	Enable support for systemd-logind.
xwayland	Enable XWayland application support.

xapian

brass	Enabled brass backend db support
chert	Enabled chert backend db support
glass	Enabled glass backend db support
inmemory	Enabled inmemory backend db support

xerces-c

iconv	Use iconv (virtual/libiconv) as message loader and transcoder (in general it would be possible to use iconv only as message loader and something else like icu or the native method as transcoder and vice-versa, but this is a less common case and hard to handle)
threads	Enable threading support through pthread (or other libraries on AIX, IRIX, HPUX, Solars). Highly recommended

xml-security-c

nss	Use dev-libs/nss for certain crypto operations (configureable at runtime)
xalan	Enable support for XSLT and XPath parsing by dev-libs/xalan-c

xmlrpc-c

abyss	Build the Abyss mini web-server.
libxml2	Use dev-libs/libxml2 to parse XML instead of the internal expat library.
threads	Controls whether to build the Abyss web-server with pthreads or fork 'threading'.
tools	Build the xmlrpc* tools.

xmlsec

gcrypt	Install xmlsec-gcrypt library
gnutls	Install xmlsec-gnutls library
nss	Install xmlsec-nss library
openssl	Install xmlsec-openssl library

xqilla

faxpp	Use dev-libs/faxpp instead of Xerces-C for certain tasks
htmltidy	Use app-text/htmltidy when parsing HTML

yaz

ziffy	Install ziffy, a promiscuous Z39.50 APDU sniffer

dev-lisp

clisp

hyperspec	Use local hyperspec instead of online version
new-clx	Build CLISP with support for the NEW-CLX module which is a -C binding to the Xorg libraries
svm	Build CLISP with support for the Support Vector Machine module

clx

doc	Builds documentation

cmucl

X	Build CLX, CLM, or Hemlock
doc	Installs package documentation
source	Include source code for CMUCL in installation

ecls

gengc	Use generational garbage collection (experimental)
libatomic	Use dev-libs/libatomic_ops library
precisegc	Use type information during garbage collection (experimental)

gcl

ansi	Build a GCL with ANSI support (else build a traditional CLtL1 image)
athena	Build xgcl - an interface to x11-libs/libXaw

sbcl

pax_kernel	Enable if the user plans to run the package under a pax enabled hardened kernel

dev-lua

luarocks

curl	Uses net-misc/curl for fetching lua packages instead of net-misc/wget.
openssl	Uses dev-libs/openssl for verifying lua packages instead of md5sum.

luvit

bundled-libs	Use bundled versions of some libraries.

dev-ml

cairo-ocaml

pango	Enable support for x11-libs/pango

csv

lwt	Enables the Lwt-based library for asynchronous operations.

dose3

parmap	Adds multi-core CPU support via dev-ml/parmap.
rpm4	Adds support for handling rpm4 files.
zip	Adds support for handling zip files.

eliom

ppx	Enable PPX syntax extension support.

js_of_ocaml

camlp4	Build with camlp4 syntax extensions.
deriving	Enable dev-ml/deriving support for improving the type safety.
lwt	Enable dev-ml/lwt support.
ppx	Enables the ppx syntax extension
react	Enable functionnal reactive programming support.

lablgtk

glade	Enable libglade bindings compilation.
gnomecanvas	Enable libgnomecanvas bindings compilation.
sourceview	Enable GtkSourceView support

logs

cli	Enables the Logs_cli library that provides command line support for controlling Logs.
fmt	Enables the Logs_fmt reporter.
lwt	Enables the Logs_lwt library that provides Lwt logging functions.

lwt

camlp4	Enable camlp4 syntax extension
libev	Enable the dev-libs/libev-based backend.
ppx	Enables the ppx syntax extension

ocaml-cohttp

async	Enables support for the dev-ml/async asynchronous execution library.
lwt	Enables support for the dev-ml/lwt cooperative light-weight thread library.

ocaml-cstruct

async	Support for asynchronous execution
lwt	Enable threads via lwt
ppx	Enable the ppx syntax extension

ocaml-websocket

async	Enables support for the dev-ml/async asynchronous execution library.
lwt	Enables support for the dev-ml/lwt cooperative light-weight thread library.

ocamlnet

httpd	Enables net-httpd web server component
zip	Enables netzip support to read/write gzip data using object channels

onanomsg

lwt	Enables lwt support.

pgocaml

camlp4	Enable PG'Ocaml syntax extension.

tyxml

camlp4	Enables the camlp4 syntax extension (deprecated)
ppx	Enables the ppx syntax extension (preferred)

uutf

utftrip	Builds and install the utftrip executable: Among other things, reads unicode on stdin and rewrites it on stdout.

zarith

mpir	Use MPIR library instead of GMP.

dev-perl

App-Nopaste

browser	Spawn browser with pasted page
clipboard	copying of URLs with -x/--copy
github	Github authentication
gitlab	Ensure git is installed for reading/passing GitLab authentication
pastebin	pastebin.com support

Business-ISBN

barcode	Install dev-perl/GD-Barcode for rendering ISBN numbers as barcodes

Config-Any

conf	Install dev-perl/Config-General to support decoding .conf/.cnf files
ini	Install dev-perl/Config-Tiny to support decoding INI config files
json	Install support libraries to support decoding JSON config files
xml	Install support libraries to support decoding XML config files
yaml	Install support libraries to support decoding YAML config files

Convert-UUlib

system-uulib	Use dev-libs/uulib instead of bundled version.

Cookie-Baker

xs	Install dev-perl/Cookie-Baker-XS for accelerated performance

Coro

ev	Build support for using dev-perl/EV as an event-loop via Coro::EV
event	Build support for using dev-perl/Event as an event-loop via Coro::Event

DBD-SQLite

system-sqlite	Use the system-wide dev-db/sqlite installation

DBD-mysql

embedded	Support embedded server (libmysqld)
ssl	Compile in support for SSL connections via libmysqlclient

DBIx-Class

admin	Modules required for the DBIx::Class administrative library
admin_script	Modules required for the CLI DBIx::Class interface dbicadmin
deploy	Modules required for "deploy" in DBIx::Class::Storage::DBI and "deploymen_statements" in DBIx::Class::Storage::DBI
replicated	Modules required for DBIx::Class::Storage::DBI::Replicated

File-HomeDir

xdg	Ensure XDG Semantics for returned paths via x11-misc/xdg-user-dirs

File-Which

pwhich	Install dev-perl/App-pwhich which used to be a part of this package

GD

animgif	Enable animated gif support
fcgi	Build for FastCGI compatibility via dev-libs/fcgi instead of using PerlIO

Graphics-ColorNames

recommended	Install recommended support modules

HTML-Mason

modperl	Enable www-apache/mod_perl support

HTTP-Entity-Parser

xs	Install C-Based dependieces for faster performance

JSON

xs	Install C-based dev-perl/JSON-XS for faster performance

JSON-MaybeXS

xs	Install a C-Based backend to make JSON encode/decode fast

Lab-VXI11

libtirpc	Build against net-libs/libtirpc for RPC support

List-MoreUtils

xs	Install C-Based backend implementation for performance

MCE

sereal	Install dev-perl/Sereal-Encoder and decoder for faster worker IPC

Mail-IMAPClient

md5	Install support for DIGEST-MD5 and CRAM-MD5 Authentication
ntlm	Install support for NTLM Authentication
ssl	Install support for SSL Connections
zlib	Install support for COMPRESS DEFLATE connections

Net-SSH2

gcrypt	Use libgcrypt instead of openssl

PDL

badval	Enable bad values support
hdf	Enable HDF (version 4) format support
netpbm	Enable NETPBM and MPEG support
pdl2	Build pdf2 shell (requires Devel-REPL)
pgplot	Enable PGPLOT plotting capabilities

Panotools-Script

gui	Installs GUIs for some tools

Ref-Util

xs	Install C-Based dev-perl/Ref-Util-XS for accelerated performance

Sub-Name

suggested	Install extra dependencies needed for extended regression tests

Sysadm-Install

hammer	Enable hammer() funtion to run a command in the shell and simulate a user hammering the ENTER key to accept defaults on prompts

Test-Warnings

suggested	Install optional dependencies for extra tests

Text-CSV

xs	Install dev-perl/Text-CSV_XS for accelerated decoding

WWW-Form-UrlEncoded

xs	Install C-Based dependieces for faster performance

perl-headers

debug	Add source locations in generated .ph files to assist with debugging when errors occur
sizeof-warning	Include logic to warn when a .ph file tries to use a sizeof() that is unknown

dev-php

PEAR-HTTP_Request2

curl	Force dev-lang/php to be compiled with curl extension
fileinfo	Force dev-lang/php to be compiled with fileinfo extension
ssl	Force dev-lang/php to be compiled with ssl extension
zlib	Force dev-lang/php to be compiled with zlib extension

PEAR-PHP_Beautifier

cli	Require dev-lang/php to be built with the "cli" SAPI and install the php_beautifier script.

agavi

executable	Install the "agavi" executable used to manage projects. This requires dev-php/phing, and may be omitted if you are (for example) deploying an existing site to a production server.

maxmind-db-reader

extension	Build the C extension that uses dev-libs/libmaxminddb

pecl-apcu

lock_pthreadmutex	Enable pthread mutex locking
lock_pthreadrw	Enable pthread read/write locking
lock_semaphore	Enable semaphore locks instead of fcntl
lock_spinlock	Enable spin locks (EXPERIMENTAL)

pecl-event

extra	Add support of the Libevent extra API

pecl-memcached

igbinary	Enable support for the igbinary serializer
json	Enable support for json serialization

pecl-mysqlnd_qc

memcached	Use dev-libs/libmemcached as a storage handler
sqlite	Use dev-db/sqlite as a storage handler

pecl-redis

igbinary	Enables igbinary serialisation support

pecl-zmq

czmq	Use the czmq high level bindings

phing

zip	Support zip archives by requiring said support in dev-lang/php.

swoole

http2	Add support for HTTP/2 protocol via net-libs/nghttp2
redis	Add support for redis via dev-libs/hiredis

twig

extension	Build the C extension (only for php-5.6.x).

xcache

coverage	Enable the coverager module (not recommended for production servers).

dev-python

Kivy

camera	Install libraries needed to support camera
garden	Install garden tool to manage user maintained widgets

PyQt5

bluetooth	Build bindings for the QtBluetooth module
dbus	Build bindings for the QtDBus module
declarative	Build bindings for the QtQml/QtQuick modules and enable the qmlscene plugin
designer	Build bindings for the QtDesigner module and enable the designer plugin
gles2	Use GLES 2.0 or later instead of full OpenGL
gui	Build bindings for the QtGui module
help	Build bindings for the QtHelp module
location	Build bindings for the QtLocation module
multimedia	Build bindings for the QtMultimedia module
network	Build bindings for the QtNetwork module
opengl	Build bindings for the QtOpenGL module
positioning	Build bindings for the QtPositioning module
printsupport	Build bindings for the QtPrintSupport module
sensors	Build bindings for the QtSensors module
serialport	Build bindings for the QtSerialPort module
sql	Build bindings for the QtSql module
svg	Build bindings for the QtSvg module
testlib	Build bindings for the QtTest module
webchannel	Build bindings for the QtWebChannel module
webengine	Build bindings for the QtWebEngine module
webkit	Build bindings for the QtWebKit module
websockets	Build bindings for the QtWebSockets module
widgets	Build bindings for the QtWidgets module
x11extras	Build bindings for the QtX11Extras module
xmlpatterns	Build bindings for the QtXmlPatterns module

PythonQt

extensions	Install extensions

QtPy

designer	Build bindings for the QtDesigner module and enable the designer plugin
gui	Build bindings for the QtGui module
svg	Build bindings for the QtSvg module
testlib	Build bindings for the QtTest module
webengine	Build bindings for the QtWebEngine module
webkit	Build bindings for the QtWebKit module

amqplib

extras	Install extra tools to generate initial Python mod from an AMQP XML file

anyvc

bazaar	Add support for Bazaar
mercurial	Add support for Mercurial

celery

redis	Enables redis support
sqs	Enables Amazon SQS transport module for celery
yaml	Enable support of yaml as a configuration file format

cgkit

3ds	Enable support for importing 3D Studio models

cvxopt

dsdp	Use interior point library sci-libs/dsdp
glpk	Use GNU Linear Programming Kit sci-mathematics/glpk

dap

server	Enable OpenDAP server support

dask

distributed	Add support for distributed computing with dev-python/distributed

django-cms

admin-style	Install plugin customizing admin panel styles
ckeditor	Install text-ckeditor plugin for rich text editing
file	Install djangocms file plugin
flash	Install djangocms flash plugin
inherit	Install djangocms inherit plugin
link	Install djangocms link plugin
picture	Install djangocms picture plugin
snippet	Install djangocms snippet plugin
teaser	Install djangocms teaser plugin
video	Install djangocms video plugin

editorconfig-core-py

cli	Install command line interface as well as python library

fabric

fab2	Install as "fab2", allowing side-by-side install with fabric 1.x

falcon

cython	Build cython-based python modules

fastparquet

brotli	Enable support for brotli compression
lz4	Enable support for lz4 compression
snappy	Enable support for snappy compression
zstd	Enable support for zstandard compression

flask-restful

paging	Enable resource paging support

geopy

timezone	Enables localized date support
yahoo	Enables use of YahooPlaceFinder

glance_store

cinder	enable cinder backend supprt
swift	enable swift backend supprt
vmware	enable vmware backend supprt

gmpy

mpir	Use sci-libs/mpir as gmp implementation

icalendar

doc	Generate examples and other extra documentation

ipython

matplotlib	Add support for dev-python/matplotlib
nbconvert	Enable support for converting notebooks to various formats using app-text/pandoc
notebook	Install requirements for the web notebook based on www-servers/tornado

jira

filemagic	Include filemagic support (for identifying uploaded filetypes)
ipython	Include Interactive Python (IPython)
jirashell	Include dependencies for jirashell (ipython, oauthlib)
kerberos	Support Kerberos authentication
oauth	Support OAuth authentication

kaa-base

tls	SSL/TLS support via dev-python/tlslite

kafka-python

snappy	Install snappy compression/decompression support

kazoo

gevent	Enable support for the gevent based handler

kombu

mongodb	Enables MongoDB backend
msgpack	Enables MessagePack (de)serializer for Python
redis	Enables Redis backend
sqs	Enables Amazon SQS transport module for Kombu
yaml	Enables yaml backend

markdown

pygments	Enable fancy pygments support

matplotlib

excel	Pull dev-python/xlwt for the exceltools toolkit
gtk2	Enable x11-libs/gtk+:2 support
gtk3	Enable x11-libs/gtk+:3 support

mpmath

matplotlib	Add support for dev-python/matplotlib

msgpack

native-extensions	Compiles native "C" extensions (speedups, instead of using python fallback code).

nbdime

webtools	Install web-based diff and merge tools.

netaddr

cli	Enable netaddr shell with dev-python/ipython

networkx

extras	Provide graph drawing and graph layout algorithms along with shapefile format reading and writing
pandas	Provides a DataFrame, which is a tabular data structure with labeled axes
scipy	Enables scipy backend
yaml	Provides YAML format reading and writing

nltk

numpy	Use numpy for the saved word tokenizer

numexpr

mkl	Enable support for Intel Vector Math Library, part of sci-libs/mkl.

pandas

full-support	Pull all packages to give pandas full support

passlib

bcrypt	bcrpyt hash algoryptm support
scrypt	accelerated scrypt algoythm support
totp	time based one time password support

paste

flup	enable support for flup (and therefore for various wgsi servers and middleware)
openid	enable OpenID support

pillow

imagequant	Build with Image Quantization Library support

py-amqp

extras	Install extra tools to generate initial Python mod from an AMQP XML file

pygame

midi	Enable midi support using media-libs/portmidi

pygpu

cuda	Enable NVIDIA CUDA toolkit support
opencl	Enable OpenCL support

pyilmbase

numpy	Add bindings for dev-python/numpy use.

pyocr

cuneiform	Enable support for the app-text/cuneiform OCR engine
tesseract	Enable support for the app-text/tesseract OCR engine

pypax

ptpax	Enable PT_PAX_FLAGS support.
xtpax	Enable XATTR_PAX_FLAGS support.

pyplusplus

indexing	Install indexing_suite_v2 to enhance boost python
numpy	Generate code for dev-libs/boost-numpy to accelerate arrays

pypy

low-memory	Build using PyPy with the engine configured towards low memory footprint. This makes it possible to build PyPy using ~3.5G of RAM on amd64 and ~half of that on x86, at the cost of lengthened build time.
sandbox	Enable sandboxing functionality

pypy3

low-memory	Build using PyPy with the engine configured towards low memory footprint. This makes it possible to build PyPy using ~3.5G of RAM on amd64 and ~half of that on x86, at the cost of lengthened build time.
sandbox	Enable sandboxing functionality

python-caja

gtk3	Build with GTK+3 instead of GTK+2

python-stdnum

vies	Enable VIES

pyudev

pygobject	Install PyGobject bindings
qt5	Install PyQt5 bindings

pyyaml

libyaml	enable support for C implementation using libyaml

pyzor

gdbm	Enables the Gdbm back-end database engine for pyzord
gevent	Use dev-python/gevent to enable asynchronous operation
mysql	Enables the MySQL back-end database engine for pyzord through dev-python/mysql-python. Only works with python-2.x!
pyzord	Enable the pyzord server daemon
redis	Enables the redis back-end database engine for pyzord through dev-python/redis-py

rarfile

compressed	Enables the module to support compressed v3 archives by calling the app-arch/unrar.

rdflib

redland	enable support for Redland triplestore

restkit

cli	Install the restcli command line interface/tool, based on dev-python/ipython

scrapy

boto	Add support for Amazon S3 via dev-python/boto
ibl	Use Instace Based Learning algorithm for automatic extraction

setuptools_scm

mercurial	Enables mercurial backend

simplecv

shell	Enable the iPython SimpleCV shell

simplespectral

faster	Use sci-libs/scipy to speed up drawing
fastest	Use dev-python/pyFFTW to speed up drawing to the max

sphinx

net	enable internet capabilities

spyder

webengine	Build bindings for the QtWebEngine module

sympy

imaging	Add support for dev-python/pillow
ipython	Add support for dev-python/ipython
mathml	Add support for mathml
pyglet	Use dev-python/pyglet for plots and print preview
symengine	Add support for a dev-python/symengine backend
texmacs	Add app-office/texmacs interface
theano	Add support for dev-python/theano

tappy

yaml	Pull dependencies needed to support YAML blocks associated with test results.

translate-toolkit

html	Support conversion between po and html files
ical	Support conversion between po and ical files
ini	Support conversion between po and ini files
subtitles	Support conversion between po and sub files
yaml	Support YAML format

twisted

conch	include Twisted SSHv2 implementation
http2	include http2 support
serial	include serial port support

twisted-core

serial	include serial port support

vatnumber

vies	Enable VIES

ws4py

client	Install client modules
server	Install server modules

wxpython

examples	Install interactive demo module browser and sample applets.

zeep

async	Add async support
tornado	Add tornado support

zsi

twisted	add support for python-twisted (needs dev-python/twisted-core and dev-python/twisted-web)

dev-qt

designer

declarative	Build the qdeclarativeview plugin
webkit	Build the qwebview plugin

linguist-tools

qml	Enable QML support in lupdate

qdoc

qml	Enable QML/JS parsing support

qt-creator

android	Build plugin for Android devices
autotools	Enable autotools project manager plugin
baremetal	Build plugin for bare metal devices
bazaar	Add support for dev-vcs/bzr version control system
clangcodemodel	Build clang-based code model and refactoring plugins
clangstaticanalyzer	Build clang-based static analyzer plugin
clearcase	Add support for IBM ClearCase version control system (requires manual installation of ClearCase client)
cmake	Enable cmake project manager plugin
designer	Build widget designer plugin
glsl	Enable GLSL source code editor
ios	Build plugin for Apple iOS devices
mercurial	Add support for dev-vcs/mercurial version control system
modeling	Enable graphical model editor
nim	Enable Nim source code editor
perforce	Add support for Perforce version control system (requires manual installation of Perforce client)
python	Enable Python source code editor
qbs	Enable QBS project manager plugin
qnx	Build plugin for QNX devices
scxml	Enable graphical SCXML editor
systemd	Add support for retrieving application output from journald
valgrind	Add support for memory debugging using dev-util/valgrind
webengine	Use dev-qt/qtwebengine to view documentation
winrt	Build plugin for WinRT devices

qt-docs

3d	Install documentation for dev-qt/qt3d
bluetooth	Install documentation for dev-qt/qtbluetooth
charts	Install documentation for dev-qt/qtcharts
datavis	Install documentation for dev-qt/qtdatavis3d
declarative	Install documentation for dev-qt/qtdeclarative, dev-qt/qtquickcontrols, and dev-qt/qtquickcontrols2
graphicaleffects	Install documentation for dev-qt/qtgraphicaleffects
html	Install documentation in HTML format
location	Install documentation for dev-qt/qtlocation
multimedia	Install documentation for dev-qt/qtmultimedia
networkauth	Install documentation for dev-qt/qtnetworkauth
qch	Install documentation in QCH format
script	Install documentation for dev-qt/qtscript
sensors	Install documentation for dev-qt/qtsensors
speech	Install documentation for dev-qt/qtspeech
virtualkeyboard	Install documentation for dev-qt/qtvirtualkeyboard
webengine	Install documentation for dev-qt/qtwebengine

qt3d

gles2	Use GLES 2.0 or later instead of full OpenGL
qml	Build QML/QtQuick bindings

qtbluetooth

qml	Build QML/QtQuick bindings and imports

qtcharts

qml	Build QML/QtQuick bindings and imports

qtcore

systemd	Enable native journald logging support

qtdatavis3d

gles2	Use GLES 2.0 or later instead of full OpenGL
qml	Build QML/QtQuick bindings and imports

qtdeclarative

gles2	Use GLES 2.0 or later instead of full OpenGL
localstorage	Build the LocalStorage import for QtQuick (requires QtSql)
widgets	Enable QtWidgets support
xml	Build the XmlListModel import for QtQuick (requires QtXmlPatterns)

qtdiag

network	Report network information
widgets	Report widget style information

qtgui

egl	Enable EGL integration
eglfs	Build the EGL Full Screen/Single Surface platform plugin
evdev	Enable support for input devices via evdev
gles2	Use GLES 2.0 or later instead of full OpenGL
ibus	Build the IBus input method plugin
libinput	Enable support for input devices via dev-libs/libinput
tslib	Enable support for touchscreen devices via x11-libs/tslib
tuio	Build plugin to receive touch events over the TUIO protocol
xcb	Build the XCB platform plugin and enable X11 integration

qtmultimedia

gles2	Use GLES 2.0 or later instead of full OpenGL
gstreamer	Enable audio support via media-libs/gstreamer using SLOT 1.0
qml	Build QML/QtQuick bindings and imports
widgets	Build the QtMultimediaWidgets module

qtnetwork

bindist	Disable EC support via dev-libs/openssl
connman	Enable net-misc/connman-based bearer plugin
libproxy	Use net-libs/libproxy for automatic HTTP/SOCKS proxy configuration
networkmanager	Enable net-misc/networkmanager-based bearer plugin

qtopengl

gles2	Use GLES 2.0 or later instead of full OpenGL

qtpositioning

geoclue	Use enhanced location information from app-misc/geoclue
qml	Build QML bindings

qtprintsupport

gles2	Use GLES 2.0 or later instead of full OpenGL

qtquickcontrols

widgets	Enable QtWidgets support

qtquickcontrols2

widgets	Enable QtWidgets support

qtscript

scripttools	Build the QtScriptTools module (requires QtWidgets)

qtsensors

qml	Build QML bindings

qtvirtualkeyboard

handwriting	Adds handwriting recognition integration support

qtwayland

libinput	Enable support for input devices via dev-libs/libinput

qtwebchannel

qml	Build QML/QtQuick bindings and imports

qtwebengine

designer	Install the QWebEngineView plugin used to add widgets in dev-qt/designer forms that display web pages.
geolocation	Enable physical position determination via dev-qt/qtpositioning
pax_kernel	Enable building under a PaX enabled kernel
system-ffmpeg	Use the system-wide media-video/ffmpeg instead of bundled.
system-icu	Use the system-wide dev-libs/icu instead of bundled.
widgets	Enable QtWidgets support

qtwebkit

geolocation	Enable physical position determination via dev-qt/qtpositioning
gles2	Use GLES 2.0 or later instead of full OpenGL
gstreamer	Enable HTML5 audio/video support via media-libs/gstreamer using SLOT 1.0
hyphen	Enable hyphenation support via dev-libs/hyphen
multimedia	Enable HTML5 audio/video support via dev-qt/qtmultimedia
orientation	Enable device orientation detection via dev-qt/qtsensors
printsupport	Enable printing via dev-qt/qtprintsupport
qml	Build QML/QtQuick bindings
webchannel	Enable integration with dev-qt/qtwebchannel
webp	Add support for WebP image format

qtwebsockets

qml	Build QML bindings

qtwidgets

gles2	Use GLES 2.0 or later instead of full OpenGL

dev-ros

rosbag

lz4	Add support for lz4 compressed bags.

rosconsole

glog	Use dev-cpp/glog as log backend.
log4cxx	Use dev-libs/log4cxx as log backend.

dev-ruby

barby

cairo	Add support for writing images (PNG, PS, EPS and, if supported, PDF and SVG) using dev-ruby/rcairo. Not available on JRuby.
png	Add support for writing PNG images using dev-ruby/chunky_png.
prawn	Add support for writing PDF documents using dev-ruby/prawn.
qrcode	Add support for QRCode 2D codes using dev-ruby/rqrcode.
rmagick	Add support for writing images (among others PNG, GIF and JPEG) using dev-ruby/rmagick. Not available on JRuby.

facter

dmi	Use sys-apps/dmidecode to determine hardware system properties
pciutils	Use sys-apps/pciutils to determine hardware system properties
virt	Use app-emulation/virt-what for virtual machine detection

faraday_middleware

mashify	Include FaradayMiddleware::Mashify
oauth	Include FaradayMiddleware::OAuth
parsexml	Include FaradayMiddleware::ParseXml
rashify	Include FaradayMiddleware::Rashify

maruku

highlight	Enable source code highlighting via dev-ruby/syntax

mysql2

mariadb	Use mariadb bindings

net-ssh

sodium	Use dev-libs/libsodium via dev-ruby/rbnacl for Ed25519 support

rails

asset-pipeline	Also install the default components for the asset pipeline. These are not required but they are activated automatically in new Rails projects by default.

rrdtool-bindings

graph	Enable support for graphing functions

rspec-core

highlight	Enable source code highlighting via dev-ruby/coderay

ruby-sdl

image	Enable media-libs/sdl-image support
mixer	Enable media-libs/sdl-mixer support
sge	Enable sdl-sge support

rubygems

server	Install support for the rubygems server

dev-scheme

gauche

mbedtls	Enable support for net-libs/mbedtls

gauche-gl

cg	Enable NVidia Cg binding

gauche-gtk

glgd	Enable GL graph draw

guile

debug-freelist	Include garbage collector freelist debugging code
debug-malloc	Include malloc debugging code
deprecated	Enable deprecated features
discouraged	(implied by deprecated) enable merely discouraged features
networking	Include networking interfaces
regex	Include regular expression interfaces

kawa

awt	Assume AWT is available
echo2	Enable support for the Echo2 web toolkit with dev-java/echo2
frontend	Build "kawa" front-end program using sys-libs/readline
jemacs	Build JEmacs
krl	Build BRL emulation and KRL
sax	Assume SAX2 is available with dev-java/sax
servlets	Build support for generating servlets with Java servletapi
swing	Assume Swing is available
xqtests	Support XQuery Test Suite

racket

futures	Enable racket/future library for fine-grained hardware parallelism
places	Enable racket/place library for share-nothing parallelism and message-passing communication. Compared to futures, places are heavyweight, but they have a simpler performance model.
threads	Enable support for green threads

scm

arrays	Support for arrays, uniform-arrays and uniform-vectors.
bignums	Support for large precision integers.
cautious	SCM will always check the number of arguments to interpreted closures.
dynamic-linking	Be able to load compiled files while running.
engineering-notation	Floats to display in engineering notation (exponents always multiples of 3) instead of scientific notation.
gsubr	generalized c arguments: for arbitrary (more then 11) arguments to C functions.
inexact	Support for floating point numbers.
ioext	Commonly available I/O extensions: line I/O, file positioning, file delete and rename, and directory functions.
libscm	Build and install libscm.a and related headers
macro	C level support for hygienic and referentially transparent macros (syntax-rules macros).
regex	String regular expression matching.
unix	Support for: nice, acct, lstat, readlink, symlink, mknod and sync.

slib

gambit	Support for gambit scheme implementation
scm	Support for scm scheme implementation

dev-tcltk

expect-lite

debug	pull in packages needed for runtime interactive debugger

tktreectrl

shellicon	shellicon extension

dev-tex

abntex

lyx	Install with app-office/lyx layout

biblatex

biber	Install the unicode compatible backend processor

circuit_macros

script	Install cm2pdf to automatically create a correctly sized PDF from a circuit_macro m4 source

dot2texi

pgf	Enable support for dev-tex/pgf (The TeX Portable Graphic Format)
pstricks	Enable pstricks support

pythontex

highlighting	Syntax highlighting using dev-python/pygments

dev-texlive

texlive-basic

luajittex	Add support for LuaJitTeX: LuaTeX based on LuaJIT which is usually faster.

dev-util

android-ndk

legacy-toolchains	Install legacy toolchains
target-32	Support for 32-bit targets
target-64	Support for 64-bit targets

anjuta

devhelp	Enable devhelp integration
glade	Build glade plugin for anjuta
packagekit	Use packagekit to search for missing tools
terminal	Enable terminal plugin based on x11-libs/vte

apitrace

cli	Enable command line interface
egl	Enable EGL support
system-snappy	Link dynamic against app-arch/snappy

bazel

tools	Install extra bazel tools to build from sources

bitcoin-tx

knots	Build enhanced Bitcoin Knots version, rather than Bitcoin Core

buildbot

docker	Add support for worker docker command steps
irc	Add support for status delivery through an ircbot.
mail	Add support for watching a maildir for commits.
manhole	Add support for manhole (debug over ssh)

bustle

interactivetests	Build interactive test programs
threaded	Build with support for multithreaded execution.

catalyst

ccache	Enables ccache support
system-bootloader	Pulls in the depends needed to setup livecd bootloader from the host system rather than using a cdtar

cccc

apidoc	Build software docs with doxygen/graphviz and metrics with cccc
mfc	Add patch for MFC dialect options

clion

custom-jdk	Install and use IntelliJ's custom JRE.

cmake

server	Enable cmake-server support.
system-jsoncpp	Use system copy of dev-libs/jsoncpp instead of bundled one.

coccigrep

vim	Install the coccigrep vim plugin

codeblocks

contrib	Build additional contrib components
fortran	Build FortranProject plugin which enables to use Code::Blocks IDE for Fortran language

cppcheck

htmlreport	install cppcheck-htmlreport

ctags

json	Enable JSON output support
xml	Enable XML parsing support
yaml	Enable YAML parsing support

cutter

jupyter	Add support for jupyter notebook
webengine	Use dev-qt/qtwebengine for in-app jupyter browser

cwdiff

a2ps	install app-text/a2ps for postscript output
mercurial	install hg wdiff alias for dev-vcs/mercurial

devhelp

gedit	Install plugin for app-editors/gedit

dialog

minimal	Disable library, install command-line program only

diffoscope

R	Use dev-lang/R
binutils	Use sys-devel/binutils
colord	Use x11-misc/colord
cpio	Use app-arch/cpio
diff	Use sys-apps/diffutils
docx	Use app-text/docx2txt
dtc	Use sys-apps/dtc
e2fsprogs	Use sys-fs/e2fsprogs
file	Use sys-apps/file
find	Use sys-apps/findutils
gettext	Use sys-devel/gettext
gpg	Use app-crypt/gnupg
haskell	Use dev-lang/ghc
hex	Use app-editors/vim-core
iso	Use virtual/cdrtools
llvm	Use sys-devel/llvm
opendocument	Use app-text/odt2txt
pascal	Use dev-lang/fpc
rpm	Use app-arch/rpm
squashfs	Use sys-fs/squashfs-tools
ssh	Use net-misc/openssh
tar	Use app-arch/tar
tcpdump	Use net-analyzer/tcpdump
xz	Use app-arch/xz-utils
zip	Use app-arch/unzip

edb-debugger

graphviz	Add support for the Graphviz library
legacy-mem-write	Probe if writes to /proc/PID/mem are broken.
pax_kernel	Enable building under a PaX enabled kernel

electron

gconf	Use gnome-base/gconf
gtk3	Use GTK+3 instead of GTK+2
lto	Build with link time optimization enabled
pic	Disable optimized assembly code that is not PIC friendly
proprietary-codecs	Enable proprietary codecs like H.264, MP3
system-ffmpeg	Use system ffmpeg instead of the bundled one
tcmalloc	Use bundled tcmalloc instead of system malloc

emilpro

system-binutils	Use the gentoo binutils instead of building against an unpatched vanilla version

fatrace

powertop	Add powetop integration

geany

gtk3	Use GTK+3 instead of GTK+2
vte	Enable Terminal support (x11-libs/vte)

geany-plugins

autoclose	Enable the autoclose plugin.
automark	Enable the automark plugin
commander	Enable the commander plugin which provides a command panel for rapid access to any action.
ctags	Enable ctags plugin
debugger	Enable the debugger plugin which interfaces with sys-devel/gdb
defineformat	Enable the defineformat plugin.
enchant	Enable spell checking using enchant
gpg	Enable geanypg plugin which integrates GPG using app-crypt/gpgme
gtk3	Use GTK+3 instead of GTK+2
gtkspell	Use gtkspell for dictionary support in GeanyVC
multiterm	Enable the multiterm plugin
overview	Enable overview plugin
pretty-printer	Enable pretty-printer plugin
scope	Enable the scope plugin which is a graphical GDB front-end
soup	Enable updatechecker and geniuspaste plugins which require net-libs/libsoup

global

vim	Integrate the GNU GLOBAL source code tag system with Vim

gnome-builder

clang	Provide integration with sys-devel/clang for best possible C/C++ autocompletion, semantic highlighting, symbol resolving, and diagnostics support
devhelp	Provide API docs browsing and integration via dev-util/devhelp
git	Provide support for the Git version control system via dev-libs/libgit2-glib (such as setup of Git for New Project, direct cloning for Open Project and changed lines indicators in the editor gutter)
sysprof	Provide an integrated profiler via dev-util/sysprof
vala	Provide an autoindenter, autocompletion, diagnostics, and symbol resolver for Vala
webkit	Enable net-libs/webkit-gtk using plugins support and the HTML/Markdown previewer plugin

google-perftools

debug	Build a set of libraries with debug support (so-called debugalloc). These are available by default but are not needed unless you're actually developing using tcmalloc.
largepages	Use (experimental) larger pages for tcmalloc, this increases memory usage, but should speed up the allocation/free operations.
minimal	Only build the tcmalloc_minimal library, ignoring the heap checker and the profilers.
optimisememory	To build libtcmalloc with smaller internal caches.

gtk-doc

highlight	Enable source code highlighting
vim	Enable source code highlighting through app-editors/vim

heaptrack

zstd	Enable support for ZSTD compression using app-arch/zstd

idea-community

custom-jdk	Install and use IntelliJ's custom JRE.

idea-ultimate

custom-jdk	Install and use IntelliJ's custom JRE.

intel-ocl-sdk

android	Install android related files
system-boost	Use system boost (dev-libs/boost) instead of bundled one
system-clang	Use system clang (sys-devel/clang) instead of bundled one
system-tbb	Use system Thread Building Blocks (dev-cpp/tbb) instead of bundled one
tools	Install Intel Offline Compiler

kdevelop

gdbui	Enable GUI for attaching GDB to a running process
hex	Enable hex editor plugin via app-editors/okteta
qmake	Enable support for QMake build system
reviewboard	Enable reviewboard support
webkit	Enable deprecated dev-qt/qtwebkit instead of dev-qt/qtwebengine for integrated documentation
welcomepage	Enable welcome page, requires dev-qt/qtdeclarative

ltrace

unwind	Use sys-libs/libunwind for frame unwinding support

lttng-tools

ust	Support LTTng-UST (Userspace Tracing)

massif-visualizer

callgraph	Enable detailed snapshot analysis using media-gfx/kgraphviewer

mdds

valgrind	Add support for memory debugging using dev-util/valgrind

mingw64-runtime

idl	Install idl files.
libraries	Build extra libraries.
tools	Build extra tools.

molecule

plugins	Add plugins provided by dev-util/molecule-plugins

nemiver

memoryview	Enable the optional hexadecimal memory inspection with app-editors/ghex

nvidia-cuda-sdk

cuda	Build CUDA binaries
opencl	Build OpenCL binaries

nvidia-cuda-toolkit

debugger	Installs the CUDA debugger
eclipse	Install plugins for eclipse
profiler	Installs the NVIDIA CUDA visual profiler

ostree

grub	Enable grub configuration generator
soup	Use libsoup for networking

perf

demangle	Enable C++ symbol name demangling, using libbfd from sys-devel/binutils. When this flag is enabled, the package will have to be rebuilt after every version bump of binutils.
doc	Build documentation and man pages. With this USE flag disabled, the --help parameter for perf and its sub-tools will not be available. This is optional because it depends on a few documentation handling tools that are not always welcome on user systems.
numa	Enable NUMA support
perl	Add support for Perl as a scripting language for perf tools.
unwind	Use sys-libs/libunwind for frame unwinding support.

pkgconf

pkg-config	Install as a replacement for dev-util/pkgconfig

pkgconfig

internal-glib	Use internal copy of dev-libs/glib

pkgconfig-openbsd

pkg-config	Install as a replacement for dev-util/pkgconfig

radare2

system-capstone	Use dev-libs/capstone instead of bundled copy.

scanmem

gui	Enable the GameConqueror GUI

schroot

btrfs	Enable support for chroots using btrfs snapshots.
dchroot	Enables the building of a wrapper named "dchroot", replacing sys-apps/dchroot.
lvm	Enable support for chroots using LVM snapshots.

squashdelta

lz4	Enable support for LZ4 compression using app-arch/lz4

squashmerge

lz4	Enable support for LZ4 compression using app-arch/lz4

strace

aio	Enable dev-libs/libaio support for tracing Asynchronous I/O operations
elfutils	Enable stack backtraces (-k flag) via dev-libs/elfutils
unwind	Enable stack backtraces (-k flag) via sys-libs/libunwind

suse-build

symlink	Provide compatibility symlinks with original openSUSE package (might clash with other packages)

sysdig

modules	Build kernel modules needed for tracing local events. Disable this only if you intend to use sysdig purely to work with dumpfiles.

sysprof

systemd	Build the sysprofd daemon service, required to run the UI without root permissions. Relies on sys-apps/systemd running as the init system.

systemtap

libvirt	Support probing of libvirt domains.

trace-cmd

udis86	Enable support for dev-libs/udis86 disassembler library

vulkan-tools

cube	Build the cube/cubepp demos
vulkaninfo	Build the vulkaninfo utility

dev-vcs

bzr

sftp	Enable sftp support

cssc

valgrind	Enable usage of dev-util/valgrind in tests

cvs

server	Enable server support

cvs2svn

bazaar	Support for dev-vcs/bzr

cvsync

gcrypt	Use dev-libs/libgcrypt for hash functions.
mhash	Use app-crypt/mhash for hash functions.
openssl	Use dev-libs/openssl for hash functions.

darcs

diff	Use 'lcs' for diff building.
http	Use the pure Haskell HTTP package for HTTP support.
network-uri	Get Network.URI from the network-uri package.
terminfo	Use the terminfo package for enhanced console support.
threaded	Use threading and SMP support.

fossil

fusefs	Enable the Fuse Filesystem
json	Enable the JSON API of Fossil's wiki
legacy-mv-rm	Enable legacy behavior for mv/rm (skip checkout files).
miniz	Use the bundled miniz for compression instead of zlib. Incompatible with ssl.
system-sqlite	Use the system SQLite instead of the bundled one
tcl-private-stubs	Enable Tcl integration via private stubs mechanism
tcl-stubs	Enable Tcl integration via stubs library mechanism
th1-docs	Enable TH1 for embedded documentation pages
th1-hooks	Enable TH1 hooks for commands and web pages

git

blksha1	Use the new optimized SHA1 implementation
cgi	Install gitweb too
curl	Support fetching and pushing (requires webdav too) over http:// and https:// protocols
gpg	Pull in gnupg for signing -- without gnupg, attempts at signing will fail at runtime!
highlight	GitWeb support for app-text/highlight
mediawiki	Support pulling and pushing from MediaWiki
mediawiki-experimental	Add experimental patches for improved MediaWiki support
pcre-jit	Enable JIT for pcre
ppcsha1	Make use of a bundled routine that is optimized for the PPC arch
subversion	Include git-svn for dev-vcs/subversion support
tk	Include the 'gitk' and 'git gui' tools
webdav	Adds support for push'ing to HTTP/HTTPS repositories via DAV

git-annex

assistant	Enable git-annex assistant and watch command
benchmark	Enable benchmarking
concurrentoutput	Use concurrent-output library (experimental)
magicmime	Use libmagic to determine file MIME types
network-uri	Get Network.URI from the network-uri package.
pairing	Enable pairing of git annex repositories
s3	Enable Amazon S3 remote
torrentparser	Use haskell torrent library to parse torrent files
webapp	Enable git-annex webapp
webdav	Enable webdav remote

gitg

glade	Install a glade catalog file
python	Install Python bindings for those plugins requiring it.

gitolite

contrib	Install user-contributed files
tools	Install tools to e.g. convert a Gitosis config to gitolite or one to check if your setup is gitolite >= 3.x compatible

gitolite-gentoo

contrib	Install user-contributed files
tools	Install tools to e.g. convert a Gitosis config to gitolite or one to check if your setup is gitolite >= 3.x compatible

kdesvn

man	Build and install man pages

mercurial

bugzilla	Support bugzilla integration.
gpg	Support signing with GnuPG.
tk	Install dev-lang/tk for hgk script.

rabbitvcs

caja	Enable extension for mate-base/caja
cli	Eanble console based frontend
diff	Use for diff command dev-util/meld
gedit	Enable plugin for app-editors/gedit
nautilus	Enable extension for gnome-base/nautilus
thunar	Enable extension for xfce-base/thunar

subversion

ctypes-python	Build and install Ctypes Python bindings
dso	Enable runtime module search
extras	Install extra scripts (examples, tools, hooks)
http	Enable http support using net-libs/serf
kwallet	Enable encrypted storage of passwords with kde-frameworks/kwallet

games-action

beathazardultra

bundled-libs	Use the upstream provided bundled libraries.

chromium-bsu

mixer	Enables media-libs/sdl-mixer sound backend instead of media-libs/openal one.

d1x-rebirth

demo	Use the demo data instead of the full game
l10n_de	Provides German translations for the game's briefings, robot descriptions, and outro of the original campaign
music	Support for ingame music
opl3-musicpack	Include alternate version of the game's music, recorded with the Yamaha YMF262 OPL3 soundchip
sc55-musicpack	Include alternate version of the game's music, recorded with the Roland Sound Canvas SC-55 MIDI module

dxx-rebirth

data	Install data files
descent1	Install Descent 1 resources and executable
descent2	Install Descent 2 resources and executable
l10n_de	Provides German translations for the game's briefings, robot descriptions, and outro of the original campaign
music	Enable music support
opl3-musicpack	Include alternate version of the game's music, recorded with the Yamaha YMF262 OPL3 soundchip
sc55-musicpack	Include alternate version of the game's music, recorded with the Roland Sound Canvas SC-55 MIDI module
textures	Include high resolution (640x480) backgrounds, briefing images and fonts (Descent 1)

hotline-miami

bundled-libs	Use bundled libraries.
launcher	Install qt launcher

minetest

jsoncpp	Enable using a system-wide JSONCPP
leveldb	Enable LevelDB backend
postgres	Optionally use PostgreSQL as map backend
redis	Enable redis backend via dev-libs/hiredis
server	Build minetest server
spatial	Enable SpatialIndex AreaStore backend

solar2

bundled-libs	Use the upstream provided bundled libraries.

supermariowar

server	Compile and install Super Mario War server files

supertuxkart

fribidi	Support for right-to-left languages
recorder	Enable recording with media-libs/libopenglrecorder
wiimote	Support for wiimote input devices

swordandsworcery

bundled-libs	Use the upstream provided bundled libraries.

trine

launcher	Install GTK+ launcher

trine-enchanted-edition

launcher	Install GTK+ launcher

trine2

launcher	Install GTK+ launcher

games-arcade

bomns

editor	enables building the level editor

burgerspace

network	Enable client-server support

commandergenius

tremor	Use media-libs/tremor as ogg decoder instead of media-libs/libvorbis

jumpnbump

music	Enable playing of background music

lbreakout2

themes	Install additional themes

moleinvasion

music	Download and install the music files

oshu

osu-skin	Include more complete osu-skin (other is minimal)

performous

midi	Enable MIDI I/O support
songs	Install a few demo songs
tools	Enable building of song extraction utilities for SingStar and Guitar Hero
webcam	Enable Webcam support

savagewheels

fmod	Enable the fmod music and sound effects library

slimevolley

net	Enable network support

tuxanci

physfs	Use dev-games/physfs instead of dev-libs/libzip to load compressed data
sound	Enable sound

games-board

cockatrice

client	Build with client
oracle	Build with oracle
server	Compile server support

crafty

no-opts	Don't try to enable crazy CFLAG options

freedoko

backgrounds	Install additional background images
gnomecards	Install the gnome-games card set
kdecards	Install the KDE card set
net	Enable network game support
openclipartcards	Install the openclipartcards card set
pysolcards	Install the PySol card set
xskatcards	Install the XSkat card set

grhino

gtp	Install the GTP (Go/Game Text Protocol) frontend

knights

speech	Enable text-to-speech support

pasang-emas

extras	Install some extra themes

pioneers

help	Enable gnome ingame help via scrollkeeper

pysolfc

extra-cardsets	Install extra cardsets
sound	Enable sound support using dev-python/pygame

spider

athena	Enable athena widgets

stockfish

armv7	Build for armv7; enables PIE
general-32	Generic unoptimized 32-bits build
general-64	Generic unoptimized 64-bits build
optimize	Enable upstream -O3 optimizations (default enabled)

tablebase-syzygy

6-pieces	Install tablebases for 6 pieces (huge!)

xboard

default-font	Install the default font that xboard uses
zippy	Enable experimental zippy client

games-emulation

dolphin

discord-presence	Enables Discord Rich Presence, show the current game on Discord
egl	Enable EGL support
evdev	Enable evdev input support
log	Increase logging output
lto	Add support for link-time optimizations.

dosbox

glide	Enable unofficial Glide emulation via media-libs/openglide

fceux

logo	Enable the ability to add a logo screen when creating AVIs

generator

sdlaudio	Enable SDL Audio

hatari

sdl2	Use libsdl2 instead of libsdl

higan

icarus	Build icarus library manager
udev	Enable udev based input

m64py

7z	Ensure support for .7z archives.
rar	Ensure support for .rar archives.

mednafen

debugger	Build with internal debugger
pax_kernel	Triggers a paxmarking of the binary

mupen64plus

audio-sdl	Enable SDL audio plugin.
input-sdl	Enable SDL input plugin.
rsp-hle	Enable HLE RSP plugin.
ui-console	Enable default console UI.
ui-m64py	Enable PyQt5 UI using games-emulation/m64py.
video-glide64mk2	Enable Glide64mk2 video plugin.
video-rice	Enable Rice video plugin.

mupen64plus-core

debugger	Build the debugger
gles2	Use GLES2 instead of OpenGL
new-dynarec	Enable new experimental dynamic recompiler implementation (only for x86 and arm)
osd	Overlay emulator messages using on-screen-display

mupen64plus-video-glide64mk2

gles2	Use GLES2 instead of OpenGL
hires	Support hi-resolution textures (requires dev-libs/boost)

mupen64plus-video-rice

gles2	Use GLES2 instead of OpenGL

nestopia

gui	Enable GUI

pcsxr

cdio	Use libcdio for CD support
sdl	Use SDL sound backend (other parts of SDL are used unconditionally)

ppsspp

headless	Build headless version of the PPSSPP
system-ffmpeg	Use the system-wide media-video/ffmpeg instead of bundled

snes9x

netplay	Enable playing ROMs over the network (not recommended)
xrandr	Enable support for the X xrandr extension

vbam

link	Enable GBA linking functionality

zsnes

debug	Enable the builtin debugger
pax_kernel	Triggers a paxmarking of the binary

games-engines

exult

sdl2	Use libsdl2 instead of libsdl

frobtads

tads2compiler	Build TADS2 compiler
tads3compiler	Build TADS3 compiler

odamex

master	Build master server target (advertises odamex server list)
odalaunch	Build the wxwidgets based launcher.
portmidi	Enable portmidi support.
server	Build server target.

openmw

devtools	Install development tools like bsatool, esmtool and opencs.

renpy

development	Install IDE for game developers and an empty game template

scummvm

fluidsynth	compile with support for fluidsynth
mpeg2	enable mpeg2 codec for cutscenes
unsupported	enable unsupported and/or broken game engines (you're on your own)

solarus

doc	Install doxygen developer documentation.

stratagus

fluidsynth	compile with support for fluidsynth

games-fps

alienarena

vidmode	Link against x11-libs/libXxf86vm. Required for full-screen support.

darkplaces

cdsound	Enables using CD audio in the engine
demo	Uses the demo data from quake1 (quake1-demodata)
lights	Install and setup the updated light maps
textures	Install and setup the updated textures

doom-data

doomsday	Add wrapper to run it within doomsday

doom3

dedicated	install only as a dedicated game server
roe	Adds support for the Resurrection of Evil expansion

doomsday

demo	Install launcher dor doom1.wad from games-fps/doom-data
doom	Install launcher for jdoom game
fluidsynth	Build the FluidSynth sound driver
fmod	Enable support for fmod music and sound effects lib
freedoom	Install launcher for doom1.wad from games-fps/freedoom
heretic	Install launcher for jheretic game
hexen	Install launcher for jhexen game
tools	Build additional tools such as doomsday-shell, md2tool and texc

duke3d-data

gog	Extract the data from the GOG.com installer.

eduke32

demo	Install the Duke Nukem 3D demo files, provided by games-fps/duke3d-demodata.
fluidsynth	Install media-libs/sdl2-mixer with fluidsynth support.
hrp	Install the Duke Nukem 3D High Resolution Pack.
offensive	Install the Duke Nukem 3D XXX Pack.
opl	Install the Duke Nukem 3D OPL music files.
psx	Install the Duke Nukem 3D PSX high resolution voice files.
sc-55	Install the Duke Nukem 3D Roland SC-55 music files.
sdk	Install the SDK files.
server	Enable support for multiplayer.
tools	Install the support tools for mapster32.
voxels	Install the Duke Nukem 3D Voxels Pack.
vpx	Enable support for media-libs/libvpx.
xmp	Enable support for media-libs/exempi.

nexuiz

maps	Install the community map pack

quake2-icculus

demo	Install the demo files (quake2-demodata) and configure for use
qmax	Build the pretty version (quake max)
rogue	Build support for the 'Ground Zero' Mission Pack (rogue)
xatrix	Build support for the 'The Reckoning' Mission Pack (xatrix)

quake3

mumble	Adds player-location (positional audio) support to VoIP
teamarena	Adds support for Team Arena expansion pack
voice	Adds VoIP support

quake3-bin

teamarena	Adds support for Team Arena expansion pack

quake3-demo

dedicated	install only as a dedicated game serer

quakeforge

wildmidi	enable libWildMidi support
xdg	enable XDG support

qudos

demo	Install the demo files (quake2-demodata) and configure for use
mods	Build support for the quake2 mission packs
qmax	Build the pretty version (quake max)
textures	Install the enhanced textures (quake2-textures)

redeclipse

dedicated	Install only as a dedicated game server

rott

demo	Install the shareware version

sauerbraten

server	Compile server support

turtlearena

mumble	Adds player-location (positional audio) support to VoIP
server	Build server target
voice	Adds VoIP support

unreal-tournament-goty

S3TC	Add the extra fancy textures to UT ... only works on certain cards (nvidia/ati/s3)

urbanterror

altgamma	Alternative way for gamma setting with modesetting driver
client	Build binary for client (includes code for non-dedicated server)
mumble	Use Mumble for ingame VoIP (experimental)
opus	Use opus as sound codec
server	Build binary for dedicated server
skeetshootmod	Build support for skeetshoot mod for specific maps
voip	Use ioq3 ingame VoIP (experimental)

worldofpadman

maps	Install extra maps (PadPack)

xonotic

ode	Enable support for physics engine from dev-games/ode

yamagi-quake2

client	Build client
ctf	Build support for the 'Capture The Flag' addon
rogue	Build support for the 'Ground Zero' Mission Pack
softrender	Build software renderer
xatrix	Build support for the 'The Reckoning' Mission Pack

games-misc

katawa-shoujo

system-renpy	Use games-engines/renpy instead of the bundled one (experimental)

little-inferno

bundled-libs	Use bundled libraries.

ponysay

fish-completion	Enable fish completion support
non-free	Install non-free ponies (i.e. from the MLP franchise)

xcowsay

fortune	Installs the fortune-mod xcow binary

games-mud

tf

atcp	enable ATCP support.
gmcp	enable GMCP support.
option102	enable telnet option 102 support.

games-puzzle

cuyo

music	Enable playing of background music

nightsky

bundled-libs	Use the upstream provided bundled libraries.

numptyphysics

user-levels	Install some fun user-created levels

pingus

music	Enable playing of background music

sgt-puzzles

gtk3	Use x11-libs/gtk+:3 instead of x11-libs/gtk+:2

tiny-and-big

bundled-libs	Use the upstream provided bundled libraries.

xlogical

alt_gfx	Use alternate graphics which are closer to the original Amiga version

games-roguelike

FTL

bundled-libs	Use bundled libraries.

angband

sound	Enable and install sounds

nethack

experimental	Enable experimental features (showscore and status_hilite)

stone-soup

ncurses	Enable for console (uses ncurses) based build. (can be enabled on top of tiles)
tiles	Enable for graphical (tiled) build. (can be enabled on top of ncurses)

tomenet

server	Compile server support

games-rpg

arx-fatalis-data

gog	Extract the data from the GOG.com installer.

arx-libertatis

c++0x	Build ROOT using the C++11 standard.
crash-reporter	Build a dev-qt/qtgui-based tool that allows to submit crash information to the upstream backtracker.
debug	Enable asserts and debug logging.
static	Link libraries statically, currently only media-libs/glew
tools	Build tools that can extract the game's data and save files.
unity-build	Build everything in one big source file, allowing for faster build times and better optimizations at the cost of higher memory usage.

daimonin-client

music	Install extra music

drascula

sound	Install optional audio files

dreamweb

doc	High-resolution scans of the written material in the original UK game box

dungeon-defenders

bundled-libs	Use the upstream provided bundled libraries.

eternal-lands-data

bloodsuckermaps	Will install Bloodsucker's Maps in place of the official map files
music	Enables in-game music
sound	Enables in-game sound effects

kqlives

cheats	Enable cheating mode

manaplus

mumble	Enable support for voice chat
pugixml	Use dev-libs/pugixml for XML parsing isntead of dev-libs/libxml2
sdl2	Use libsdl2 instead of libsdl

sumwars

tools	Builds editor tools

to-the-moon

bundled-libs	Use bundled libraries

games-simulation

corsix-th

midi	Adds support for background MIDI music via SDL_mixer

flightgear

dbus	Enable screensaver DBus interaction
gdal	Enable alternative terrain engine based on pagedLOD using sci-libs/gdal
qt5	Build Qt5 launcher application
udev	Enable event-based Input devices through virtual/udev
utils	Build various utilities (fgpanel, fgviewer among others)

openrct2

multiplayer	Enable multiplayer functionality
twitch	Enable Twitch support

openttd

aplaymidi	Enables midi music in game, using aplaymidi as an external player
dedicated	Build only the openttd server, and not the client.
lzo	Enables LZO compression for savegames. This is only needed to load extremely old savegames. (versions before 0.2)
openmedia	Enables the free open media sets: OpenGFX, OpenSFX, OpenMSX, removing the requirement for proprietary TTD assets to play OpenTTD.

singularity

music	Install music files

games-sports

speed-dreams

xrandr	Enable support for the X xrandr extension

xmoto

double-precision	more precise calculations at the expense of speed
editor	Depend on inkscape, scripts to convert svg to level (svg2lvl)

games-strategy

0ad

editor	Include Atlas scenario editor projects
lobby	Enable the use of net-libs/gloox and the multiplayer lobby
nvtt	Support for some uncompressed data formats via media-gfx/nvidia-texture-tools (might be needed for some mods)

colobot

devbuild	TODO
tools	Build tools

colobot-data

music	Enable music support
music_flac_convert	Fetch flac music and convert it to ogg
music_ogg	Fetch ogg music

defcon-demo

system-libs	Use system libraries instead of the ones included in the upstream distribution.

freeciv

aimodules	Support for dynamically loadable AI modules (server-side)
auth	Add authentication capability via mysql, postgres or sqlite3
mapimg	Additional mag image toolkit via media-gfx/imagemagick
modpack	Build the freeciv-modpack-program to download/install mods
server	Enable server support. Disabling this will also make it impossible to start local games.
sound	Add support for sound provided by media-libs/sdl-mixer
system-lua	Use dev-lang/lua instead of the bundled liblua

freesynd

devtools	Build development tools

hedgewars

server	Enable local server

heroes3

maps	Installs optional map data
music	Installs optional music data
sounds	Installs optional sound data

ja2-stracciatella

editor	Adds necessary file to run the editor
ru-gold	Support for russian gold ja2 version

liquidwar6

doc	Convert the info pages to html
gles2	Enable OpenGL ES 2.0 support
gtk	Used to display error/critical messages
maps	Install extra maps
ogg	Enable mod-ogg via media-libs/sdl-mixer (currently the only sound provider)
readline	Enable interactive script shell for hacking

megaglest

editor	Build map editor
fribidi	Enable FriBIDi support
model-viewer	Build model viewer
streflop	Use the library streflop. Out of synchs may occur if not enabled.
tools	Build model import/export tools
unicode	Use unicode strings for wxwidgets
wxuniversal	Use the wxUniversal port which implements the various GUI controls by drawing them itself

naev

mixer	Enables media-libs/sdl-mixer sound backend in addition to media-libs/openal one.

ufoai

client	Build the main game client
editor	Build the map editor and compiler
server	Build the dedicated server

uqm

music	download and install music files (large)
remix	download and install music remix files (large)
voice	download and install voice files (large)

wesnoth

fribidi	Support for right-to-left languages
server	Enable compilation of server

games-util

gslist

web	Enable the web interface

pyfa

graph	Enable support for graphs

wit

fuse	Enable image mount support via fuse

gnome-base

gconf

ldap	Build backend which enables default mail accounts, addressbooks and calendars for Evolution to be configured using each user's LDAP entry."

gdm

fprint	Enables experimental fingerprint authentication using sys-auth/fprintd
plymouth	Enable support for smooth transition from sys-boot/plymouth

gnome

classic	Install gnome-extra/gnome-shell-extensions for the Gnome Shell Classic mode
extras	Install additional GNOME applications

gnome-common

autoconf-archive	Pull in sys-devel/autoconf-archive for ax_*.m4 files instead of installing them from the gnome-common tarball

gnome-control-center

colord	Support color management using x11-misc/colord
gnome-online-accounts	Enable configuration panel for net-libs/gnome-online-accounts accounts
ibus	Enable support for enhanced input methods through app-i18n/ibus

gnome-desktop

license-docs	Install help files documenting GNOME's licenses

gnome-extra-apps

games	Install Gnome Games
share	Install the gnome-extra/gnome-user-share personal file sharing tool
shotwell	Install the media-gfx/shotwell photo manager
tracker	Install the app-misc/tracker indexer and the GNOME packages that require it

gnome-keyring

ssh-agent	Use GNOME Keyring to unlock SSH keys. Recommended unless you are using ECDSA or Ed25519 keys.

gnome-light

gnome-shell	Install gnome-base/gnome-shell and x11-wm/mutter for the standard GNOME 3 desktop mode

gnome-settings-daemon

colord	Support color management using x11-misc/colord
openrc-force	Skip systemd dependency (#480336), enabling this flag will become your setup to be fully unsupported by upstream and downstream Gnome team. Do not try to enable it unless completely needed

gnome-shell

browser-extension	Ensure the presence of extensions.gnome.org native connector gnome-extra/chrome-gnome-shell
ibus	Enable support for enhanced input methods through app-i18n/ibus
openrc-force	Skip systemd dependency (#480336), enabling this flag will become your setup to be fully unsupported by upstream and downstream Gnome team. Do not try to enable it unless completely needed

gvfs

afp	Enables support for accessing AFP (Apple Filing Protocol) network shares
archive	Enables support for accessing files in archives transparently via app-arch/libarchive
bluray	Enable playback of Blu-ray filesystems using media-libs/libbluray
elogind	Use sys-auth/elogind for session tracking.
fuse	Enables fuse mount points in $HOME/.gvfs for legacy application access
gnome-online-accounts	Enable configuration panel for net-libs/gnome-online-accounts accounts
google	Enables support for accessing Google accounts via dev-libs/libgdata
http	Enable the HTTP/DAV backend using net-libs/libsoup
nfs	Enable NFS client support via net-fs/libnfs.
udev	Enable udev base replacement code for cdda feature

libglade

tools	Install libglade-convert Python script.

libgnomecanvas

glade	Enable glade support

librsvg

tools	Build svg viewer tool

nautilus

packagekit	Use packagekit to search for programs to open unknown file types
previewer	Use gnome-extra/sushi to preview files from the file mananger
sendto	Enable the nautilus-sendto extension to send files to various locations/devices
tracker	Add support for app-misc/tracker search

orbit

pic	Force libname-server-2 to be built as PIC; needed on hardened systems

gnome-extra

cinnamon-control-center

colord	Support color management using x11-misc/colord

cinnamon-settings-daemon

colord	Support color management using x11-misc/colord

evolution-data-server

api-doc-extras	Build documentation for private APIs
berkdb	sys-libs/db support needed to migrate old (pre-3.12 evolution versions) addressbook data
gnome-online-accounts	Enable net-libs/gnome-online-accounts based Google authentication support
google	Enable internal Google authentication support. If gnome-online-accounts is enabled and used, this is not necessary, but both can be supported at the same time with different setup at runtime
weather	Enable optional weather calendar support

gnome-color-manager

packagekit	Enable support for the distro-neutral package manager GUI app-admin/packagekit

gnome-commander

chm	Enable metadata support for Microsoft Compiled HTML Help files
gsf	Add metadata support for OLE, OLE2 and ODF
pdf	Add metadata support for PDF
python	Add support for python plugins
samba	Add support for SAMBA (Windows File and Printer sharing)
taglib	Add metadata support for ID3, Vorbis, FLAC and APE
unique	Enable single instance support using dev-libs/libunique

gnome-dvb-daemon

totem	Build a plugin for media-video/totem

gnome-system-monitor

systemd	Display sys-apps/systemd metadata, e.g. unit names, for running processes

libgda

canvas	Enable support for x11-libs/goocanvas
http	Enable embedded net-libs/libsoup based server
json	Enable support for JSON format
mdb	Enable support for Microsoft Access database using app-office/mdbtools
reports	Install tools for generating graphical reports
sourceview	Enable support for x11-libs/gtksourceview

libgsf

gtk	Enable use of gdk in thumbnailer

nemo

packagekit	Use packagekit to search for programs to open unknown file types
tracker	Add support for app-misc/tracker search

nm-applet

gcr	Enable advanced certificate chooser, requires app-crypt/gcr
modemmanager	Enable support for mobile broadband devices using net-misc/modemmanager
teamd	Enable teamd configuration editor

sushi

office	Support viewing file formats such as generated by app-office/libreoffice

synapse

plugins	Build support for plugins using librest

gnustep-apps

gemas

projectcenter	Build and install plugin for gnustep-apps/projectcenter

gworkspace

gwmetadata	Enable the metadata indexing and searching system

gnustep-base

gnustep-back-art

xim	Enable X11 XiM input method

gnustep-back-cairo

xim	Enable X11 XiM input method

gnustep-back-xlib

xim	Enable X11 XiM input method

gnustep-gui

speech	Audio support using app-accessibility/flite

gnustep-make

libobjc2	Enables use of the GNUstep Objective-C runtime (gnustep-base/libobjc2) with non-fragile ABI and sys-devel/clang compiler
native-exceptions	Enables use of the native Objective-C exception support (@try/@catch/@finally) built-in objective-c exceptions with compilers that support it

libobjc2

boehm-gc	Enable Hans Boehm's garbage collector (dev-libs/boehm-gc). Not recommended by upstream

kde-apps

akonadi

designer	Install plugin for dev-qt/designer
tools	Install tools for developers and testing

analitza

eigen	Enable dev-cpp/eigen mathematical templates support

ark

zip	Enable ZIP archive support via dev-libs/libzip

artikulate

qtmedia	Enable playback via Qt5Multimedia

cantor

R	Enable dev-lang/R backend support
analitza	Enable kde-apps/analitza backend support
julia	Enable dev-lang/julia backend support
qalculate	Enable sci-libs/libqalculate backend support

dolphin

thumbnail	Enables thumbnail generation

dolphin-plugins

bazaar	Enable support for the bazaar VCS
dropbox	Enable support for the dropbox fileviewer plugin
git	Enable support for the git VCS
mercurial	Enable support for the mercurial VCS

gwenview

activities	Enable kactivities support
fits	Enable support for NASA's sci-libs/cfitsio library
kipi	Enable support for the KDE Image Plugin Interface
mpris	Enable support for MPRIS2 interface, requiring dev-qt/qtdbus as dependency.

k3b

emovix	Enable burning support for eMoviX images

kalzium

editor	Enable the embedded molecule editor/viewer
solver	Enable the equation solver

kanagram

speech	Enable text-to-speech support

kate

addons	Build and install additional plugins

kde-apps-meta

pim	Pull in KDE PIM suite
sdk	Pull in developer-specific meta-packages

kdeadmin-meta

cron	Installs KDE application for virtual/cron configuration

kdeedu-meta

webengine	Enable kde-apps/kalzium and kde-apps/parley, requiring dev-qt/qtwebengine

kdegraphics-mobipocket

thumbnail	Enables thumbnail generation

kdemultimedia-meta

cdrom	Include packages for optical discs

kdenetwork-meta

telepathy	Enable support for Plasma Telepathy (instant messaging) integration via kde-apps/plasma-telepathy-meta

kdenlive

freesound	Enable freesound.org credentials support via dev-qt/qtwebkit to download files
gles2	Use GLES 2.0 or later instead of full OpenGL
jogshuttle	Enable support for Jog-Shuttle devices
share	Enable support for a share menu using kde-frameworks/purpose

kdepim-addons

importwizard	Enable additional import plugins for kde-apps/akonadi-import-wizard

kdepim-runtime

speech	Enable text-to-speech support

kdeutils-meta

floppy	Install kde-apps/kfloppy to format and create DOS or ext2fs filesystems in a floppy.

keditbookmarks

man	Build and install man pages

kget

bittorrent	Enable bittorrent transfer plugin through net-libs/libktorrent
gpg	Enable signature verification by GpgME++ via app-crypt/gpgme
mms	Enable MMS (Microsoft Media Server) plugin through media-libs/libmms

kig

geogebra	Support files created by sci-mathematics/geogebra
scripting	Support Python scripting

kio-extras

activities	Enable activities kioslave and fileitem plugin
htmlthumbs	Enable HTML thumbnail previews via dev-qt/qtwebengine
man	Enable manpages kioslave
phonon	Enable file audio preview plugin using media-libs/phonon
sftp	Enable SFTP protocol support using net-libs/libssh
taglib	Enable audio thumbnails via media-libs/taglib

kmag

keyboardfocus	Enable keyboard focus tracking

konqueror

activities	Enable kactivities support
speech	Build text-to-speech plugin
webengine	Enable dev-qt/qtwebengine as web browser engine (fallback is kde-misc/kwebkitpart)

kopete

addbookmarks	Automatically add incoming urls to bookmarks.
autoreplace	Automatically replace selected text
contactnotes	Enables writing personal notes for contacts.
gadu	Enable the Gadu protocol handler.
groupwise	Enable the Groupwise protocol handler.
highlight	Allows you to specify highlights on specific events.
history	Enables saving chat history.
latex	Embed latex formatted text into messages.
meanwhile	Enable the Sametime protocol handler.
nowlistening	Shows song you currently listen to in your status/etc. Bindings for many players.
otr	Allows crypting your chat (drugs and talking nonsense are considered as good alternatives ;]).
pipes	Send messages to external pipe.
privacy	Filter for incoming messages
statistics	Everybody loves statistic graphs, especially cake ones. ;]
testbed	Enable the testbed protocol.
texteffect	Various fancy text effects for your messages (don't ever consider writing us with this enabled ;]).
translator	Translate incoming and outgoing messages.
urlpicpreview	Enables in conversation pictures preview.
webpresence	Show your status and some more information on web.
winpopup	Enable pop-up messages sending on windows. (same as good old "net send" messages ;])
zeroconf	Enable Link-Local Messaging via the bonjour protocol.

kpimtextedit

designer	Build plugins for dev-qt/designer
speech	Enable text-to-speech support

ktp-accounts-kcm

experimental	Enables disabled telepathy services (currently only steam)

ktp-common-internals

otr	Enable support for encrypted conversations using Off-The-Records messaging
sso	Enable support for Single sign-on through KAccounts

ktp-text-ui

speech	Enable incoming messages to be read out using text-to-speech

kwave

opus	Enable Opus audio codec support
qtmedia	Enable playback via Qt5Multimedia

libkdepim

designer	Build plugins for dev-qt/designer

libksane

kwallet	Enable encrypted storage of passwords with kde-frameworks/kwallet

mailcommon

designer	Build plugins for dev-qt/designer

marble

aprs	Enable support for APRS data sources
designer	Install plugin for dev-qt/designer
phonon	Enable sound support via media-libs/phonon
shapefile	Enable support for ESRI shapefiles

okular

chm	Enable support for Microsoft Compiled HTML Help files
epub	Enable E-Book support via app-text/ebook-tools
image-backend	Enable image viewing support
markdown	Enable Markdown support via app-text/discount
mobi	Enable mobipocket support
mobile	Enable Plasma mobile support
plucker	Enable Plucker E-Book for Palm OS devices support
share	Enable support for a share menu using kde-frameworks/purpose
speech	Enable text-to-speech support

pimcommon

designer	Build plugins for dev-qt/designer

spectacle

kipi	Enable support for the KDE Image Plugin Interface
share	Enable support for a share menu using kde-frameworks/purpose

step

qalculate	Enable the libqalculate library for unit conversion

kde-frameworks

frameworkintegration

appstream	Enable AppStream software metadata support

kconfigwidgets

man	Build and install man pages

kded

man	Build and install man pages

kdesignerplugin

designer	Build KF5 widgets plugin for QtDesigner
webkit	Build kdewebkit plugin for QtDesigner

kfilemetadata

epub	Enable support for reading EPUB ebook metadata
office	Enable support for reading ODF and OOXML metadata

kimageformats

eps	Support the EPS graphics file format

kinit

caps	Capabilities support for improved security and better OOM handling
man	Build and install man pages

kio

kwallet	Enable permanent storage of passwords for kpasswdserver with kde-frameworks/kwallet

knotifications

phonon	Play notification sounds via media-libs/phonon instead of media-libs/libcanberra
speech	Enable text-to-speech notification support

knotifyconfig

phonon	Add sound support via media-libs/phonon

kpackage

man	Build and install man pages

kservice

man	Build and install man pages

ktexteditor

editorconfig	Enable support for EditorConfig configuration files

ktextwidgets

speech	Enable text-to-speech support

kwallet

gpg	Support wallets with GnuPG encryption in addition to the default blowfish-encrypted file
man	Build and install man pages

kxmlgui

attica	Enable support for kde-frameworks/attica

networkmanager-qt

teamd	Enable Teamd control support

plasma

gles2	Use GLES 2.0 or later instead of full OpenGL

prison

qml	Enable QML/QtQuick support via dev-qt/qtdeclarative

purpose

kaccounts	Enable support for system-wide defined KAccounts

sonnet

aspell	Enable the app-text/aspell spell-checking backend
hunspell	Enable the app-text/hunspell spell-checking backend

kde-misc

kdeconnect

app	Enable experimental kcapp frontend
mousepad	Enable remote mousepad plugin using x11-libs/libfakekey
wayland	Enable kwin_wayland support for mousepad plugin using kde-frameworks/kwayland

kimtoy

scim	Enable Smart Common Input Method support

kio-gdrive

kaccounts	Use kde-apps/kaccounts-integration backend (default) instead of dev-libs/qtkeychain

kmarkdownwebview

webkit	Use dev-qt/qtwebkit instead of dev-qt/qtwebengine

tellico

discid	Add support for reading disc IDs from audio CDs

kde-plasma

kde-cli-tools

kdesu	Build graphical frontend for kde-frameworks/kdesu

kdeplasma-addons

dictionary	Enable dictionary applet using dev-qt/qtwebengine
share	Enable applet for quickly sharing data to a variety of sources
webengine	Enable dictionary and web browser applets using dev-qt/qtwebengine

kinfocenter

gles2	Show OpenGL ES information in kinfocenter
pci	Show advanced PCI information

kmenuedit

hotkeys	Enable support for hotkey editing

kscreenlocker

consolekit	Add support for killing the screenlocker when sys-auth/consolekit is the session tracker

kwin

gles2	Use OpenGL ES 2 instead of full GL
multimedia	Enable effect video button in desktop effects KCM

libksysguard

detailedmemory	Enable display of detailed memory information using dev-qt/qtwebkit.

plasma-desktop

appstream	Enable AppStream software metadata support
ibus	Use ibus input method via app-i18n/ibus
mouse	Enable mouse KCM
scim	Enable applets that use app-i18n/scim
touchpad	Enable touchpad KCM

plasma-meta

browser-integration	Enable integration with Chrome/Firefox with browser extensions
crypt	Pull in kde-plasma/plasma-vault for encrypted vaults integration
display-manager	Pull in a graphical display manager
grub	Pull in Breeze theme for sys-boot/grub
gtk	Enable Breeze widget style and KCM for GTK2 and GTK3
legacy-systray	Add support for GTK+ applications using legacy xembed systray icons
pam	Enable support for kwallet auto-unlocking
plymouth	Pull in Breeze theme for sys-boot/plymouth
pulseaudio	Install Plasma applet for PulseAudio volume management
sddm	Pull in the x11-misc/sddm display manager and KCM
sdk	Pull in kde-plasma/plasma-sdk for Plasma development
wallpapers	Install wallpapers for the Plasma Workspace

plasma-nm

modemmanager	Enable support for mobile broadband devices
openconnect	Build support for the OpenConnect VPN client
teamd	Enable Teamd control support

plasma-workspace

appstream	Enable AppStream software metadata support
geolocation	Enables dataengine providing location information
prison	Enable support for barcodes/QRcodes
qalculate	Enable Qalculate runner using sci-libs/libqalculate

powerdevil

brightness-control	Enable screen brightness control using app-misc/ddcutil
consolekit	Enable sys-auth/consolekit support instead of logind session tracking
wireless	Enable wireless energy saving actions via kde-frameworks/bluez-qt and kde-frameworks/networkmanager-qt

systemsettings

classic	Enable classic mode plugin, requires kde-frameworks/khtml

lxde-base

lxdm

consolekit	Enables support for authorization using consolekit
gtk3	Use GTK+3 instead of 2

lxterminal

gtk3	Use GTK+3 instead of GTK+2

lxqt-base

lxqt-config

monitor	Build monitor settings tool

lxqt-meta

about	Install lxqt-base/lxqt-about
admin	Install lxqt-base/lxqt-admin
filemanager	Install x11-misc/pcmanfm-qt file manager
icons	Install an icon theme
lightdm	Install x11-misc/lightdm display manager
lximage	Install media-gfx/lximage-qt image viewer
minimal	Do not install x11-wm/openbox window manager
oxygen	Prefer kde-frameworks/oxygen-icons (default)
powermanagement	Install lxqt-base/lxqt-powermanagement package
processviewer	Install x11-misc/qps package
screenshot	Install x11-misc/screengrab package
sddm	Install x11-misc/sddm display manager
ssh-askpass	Install lxqt-base/lxqt-openssh-askpass user password prompt tool
sudo	Install lxqt-base/lxqt-sudo
terminal	Install x11-terms/qterminal package

lxqt-panel

clock	Build clock plugin
colorpicker	Build colorpicker plugin
cpuload	Build cpuload plugin
desktopswitch	Build desktopswitch plugin
directorymenu	Build directorymenu plugin
dom	Build dom plugin
kbindicator	Build kbindicator plugin
mainmenu	Build mainmenu plugin
mount	Build mount plugin
networkmonitor	Build networkmonitor plugin
quicklaunch	Build quicklaunch plugin
sensors	Build sensors plugin
showdesktop	Build showdesktop plugin
spacer	Build spacer plugin
statusnotifier	Build statusnotifier plugin
sysstat	Build sysstat plugin
taskbar	Build taskbar plugin
tray	Build tray plugin
volume	Build volume plugin
worldclock	Build worldclock plugin

lxqt-session

themes	Install LXQt themes and graphics

mail-client

alot

doc	Install user manual and API documentation

alpine

chappa	enhance alpine by applying Eduardo Chappa's patches
onlyalpine	installs only the alpine binary, so it does not collied with pico and/or pine
passfile	Adds support for caching passwords into a file between sessions
smime	Enable support for S/MIME

balsa

crypt	Adds support for GnuPG encryption
rubrica	Adds support for rubrica addressbook

claws-mail

archive	Enable archiving plugin
bogofilter	Build mail-filter/bogofilter plugin
dillo	Enable dillo html viewer plugin
gdata	Enable plugin for access to Google data providers
gtk3	Build support for GTK+3
libcanberra	Enable sound notification in connection with USE=notification
libindicate	Enable notification through DBUS in connection with USE=notification
libnotify	Enable notification on the desktop in connection with USE=notification
notification	Notification for new mail in different way, see also USE flags libcanberra, libindicate and libnotify
pgp	Enable PGP support
sieve	Build plugin for sieve filter support
smime	Build plugin for S/MIME support
spam-report	Enable plugin for spam reporting to various services
spamassassin	Build mail-filter/spamassassin plugin
valgrind	Add support for memory debugging using valgrind

evolution

archive	Enable archives support in attachments via app-arch/gnome-autoar
bogofilter	Build mail-filter/bogofilter plugin
crypt	Enable GPG encryption support using app-crypt/gnupg and app-crypt/pinentry
geolocation	Enable support for displaying contacts on a map inside evolution using media-libs/libchamplain
highlight	Enable text highlighting plugin
ldap	Enable support for fetching contacts from an LDAP or Active Directory server using net-nds/openldap
spamassassin	Build mail-filter/spamassassin plugin
weather	Enable optional weather calendar support
ytnef	Enable optional TNEF attachments parser support using net-mail/ytnef

mail-notification

sylpheed	Enable support for MH mailboxes used by mail-client/sylpheed

mutt

berkdb	Enable sys-libs/db database backend for header caching
crypt	Add support for encryption -- using mcrypt or gpg where applicable
gdbm	Enable sys-libs/gdbm database backend for header caching
gpg	Enable support for app-crypt/gpgme
gpgme	Build gpgme backend to support S/MIME, PGP/MIME and traditional/inline PGP
hcache	Enable header cache, one database backend needs to be enabled
lmdb	Enable dev-db/lmdb database backend for header caching
notmuch	Enable support for net-mail/notmuch
pgp_classic	Build classic_pgp backend to support PGP/MIME and traditional/inline PGP
pop	Enable support for POP3 mailboxes
sidebar	Enable the sidebar feature
smime	Enable support for smime
smime_classic	Build classic_smime backend to support S/MIME
smtp	Enable support for direct SMTP delivery
tokyocabinet	Enable dev-db/tokyocabinet database backend for header caching

nail

kerberos	If network is enabled, this adds support for GSSAPI login on IMAP through virtual/krb5.
net	Enable support for network protocols (POP, IMAP and SMTP). If you only need to send mail with the local Transport Agent, disabling this will get you support for only /usr/sbin/sendmail call.
ssl	If network is enabled, this adds support for S/MIME and SSL/TLS-powered protocols through dev-libs/openssl.

neomutt

berkdb	Enable BDB (Berkley DB) backend for header caching
crypt	Add support for encryption -- using mcrypt or gpg where applicable
gdbm	Enable GDBM (GNU dbm) backend for header caching
gpg	Enable support for app-crypt/gpgme
gpgme	Build gpgme backend to support S/MIME, PGP/MIME and traditional/inline PGP
kyotocabinet	Enable Kyoto Cabinet database backend for header caching
lmdb	Enable LMDB (Lightning Memory-Mapped Database) backend for header caching
notmuch	Enable support for net-mail/notmuch
pgp_classic	Build classic_pgp backend to support PGP/MIME and traditional/inline PGP
qdbm	Enable QDBM (Quicker Database Manager) database backend for header caching
smime	Enable support for smime
smime_classic	Build classic_smime backend to support S/MIME
tokyocabinet	Enable Tokyo Cabinet database backend for header caching

roundcube

change-password	Allow users to change passwords through Roundcube
enigma	Add dependencies to support server-side GnuPG signing and/or encryption through the enigma plugin
ldap	Add dependencies to support connecting to an LDAP address book server
managesieve	Add dependencies to support the sieverules plugin

sylpheed

oniguruma	Use dev-libs/oniguruma for regular expression

thunderbird

bindist	Disable official Thunderbird branding (icons, name) which are not binary-redistributable according to upstream.
crypt	Enable encryption support with enigmail
custom-optimization	Build with user-specified compiler optimizations (-Os, -O0, -O1, -O2, -O3) from CFLAGS (unsupported)
gtk2	Use the cairo-gtk2 rendering engine instead of the default cairo-gtk3
jemalloc	Enable or disable jemalloc
jemalloc3	Enable or disable jemalloc3 (forced-on when supported prior to 38.0)
lightning	Enable app-global calendar support (note 38.0 and above bundles calendar support when this flag is off)
minimal	Remove the software development kit and headers
mozdom	Enable Mozilla's DOM inspector
rust	Enable support for using rust compiler (experimental)
system-cairo	Use the system-wide x11-libs/cairo instead of bundled.
system-harfbuzz	Use the system-wide media-libs/harfbuzz and media-gfx/graphite2 instead of bundled.
system-icu	Use the system-wide dev-libs/icu instead of bundled.
system-jpeg	Use the system-wide media-libs/libjpeg-turbo instead of bundled.
system-libevent	Use the system-wide dev-libs/libevent instead of bundled.
system-libvpx	Use the system-wide media-libs/libvpx instead of bundled.
system-sqlite	Use the system-wide dev-db/sqlite installation with secure-delete enabled

thunderbird-bin

crashreporter	Enable crash reporter for bugs

trojita

password	Store passwords securely via dev-libs/qtkeychain

mail-filter

MailScanner

exim	Set mail-mta/exim to used MTA
postfix	Set mail-mta/postfix to used MTA
spamassassin	Enable usage of mail-filter/spamassassin for spam protection

amavisd-new

courier	Add courier support
dkim	Add DomainKeys Identified Mail support
qmail	Add qmail support
razor	Add support for mail-filter/razor
spamassassin	Add support for mail-filter/spamassassin
zmq	Add support for zeromq sockets

ask

procmail	Adds support for mail-filter/procmail

assp

spf	Adds support for Sender Policy Framework
srs	Adds support for Sender Rewriting Scheme

bogofilter

tokyocabinet	Enable Tokyo Cabinet database support

clamassassin

clamd	Use the app-antivirus/clamav daemon for virus checking
subject-rewrite	Adds support for subject rewriting

dcc

rrdtool	Enable net-analyzer/rrdtool interface scripts

dspam

daemon	Enable support for DSPAM to run in --daemon mode
debug	Enable debugging support (don't enable this unless something needs testing!)
domain-scale	Build for domain scale setups - puts data to $HOME/data/domain.com/user
hash	Enable support for the file-orientated hash driver
large-scale	Build for large scale setups - puts data to $HOME/data/u/s/user
small-scale	Build for small scale setups - puts data to $HOME/data/user
user-homedirs	Build with user homedir support
virtual-users	Build with virtual-users support

libmilter

poll	Use poll instead of select

maildrop

authlib	Add courier-authlib support
dovecot	Add dovecot authentication support
tools	Install maildirmake and deliverquota tools
trashquota	Count deleted messages as part of the maildir quota

mimedefang

poll	Use poll instead of select

opendkim

ldap	Enable openldap as a dataset facilitator or keys, determining domains to sign for, and any other dataset that opendkim supports.
lmdb	Add support for using dev-db/lmdb
lua	Enables control over signature verification, filtering and policy to be controlled by user defined lua scripts.
memcached	Add support for using dev-libs/libmemcached
opendbx	Use opendbx backend to facilitate dataset driven OpenDKIM configuration options like stats, bodylengthdb, etc. against a wide variety of database types
poll	Use poll() instead of select() for the provided asynchronous resolver library.
sasl	Used to authenticate to a LDAP server in various ways if required.
unbound	Use the unbound dnssec library to perform DKIM DNS queries.

opendmarc

reports	Install the reports binaries: expire, import, reports, params
spf	Use the mail-filter/libspf2 for Sender Policy Framework checking

opensmtpd-extras

filter-clamav	filter for scanning with app-antivirus/clamav
filter-dkim-signer	filter for adding DKIM signatures to outgoing messages
filter-dnsbl	filter for checking hosts against the DNS black lists
filter-lua	filter for interfacing with dev-lang/lua
filter-monkey	filter for arbitrarily rejecting random emails
filter-pause	filter to pause on new connections
filter-perl	filter for interfacing with dev-lang/perl
filter-python	filter for interfacing with dev-lang/python
filter-regex	filter for regular expression matching
filter-spamassassin	filter for scanning with mail-filter/spamassassin
filter-stub	stub filter
filter-trace	trace filter
filter-void	void filter
queue-null	null queue
queue-python	queue for interfacing with dev-lang/python
queue-ram	ram queue
queue-stub	stub queue
scheduler-python	schedulre for interfacing with python
scheduler-ram	ram scheduler
scheduler-stub	stub scheduler
table-ldap	table for lookups with net-nds/openldap
table-mysql	table for lookups with virtual/mysql
table-passwd	table for lookups using /etc/passwd
table-postgres	table for lookups with dev-db/postgresql
table-python	table for interfacing with dev-lang/python
table-redis	table for lookups with dev-db/redis
table-socketmap	table for lookups using a socket map
table-sqlite	table for lookups with dev-db/sqlite3
table-stub	stub table

postfwd

tools	Install additional tools for testing postfwd

postgrey

targrey	Enables the targrey patch

rmilter

dkim	Enable support for DomainKeys Identified Mail
memcached	Enable support for memcached

rspamd

fann	Enable neural network plugin (requires sci-mathematics/fann).
jemalloc	Use dev-libs/jemalloc for allocations
pcre2	Use dev-libs/libpcre2
torch	Enable torch support. This is required for the neural module

spamassassin

cron	Install a cron job to update SpamAssassin's rules daily.
qmail	Build qmail functionality and docs

spamdyke

ssl	Enables TLS protocol for spamdyke

zdkimfilter

debug	Log process and signal information. Also leave the child process running for gdb examination.
opendbx	An alternate statistics based storage engine.

mail-mta

courier

fax	Enables fax support in the courier mail server
norewrite	Prevents courier mail server from mangling virtual user addresses when sending
web	Enable the web interface
webmail	Enable the webmail interface

exim

arc	Adds support for Authenticated Receive Chain (ARC)
dane	Adds support for DNS-based Authentication of Named Entities
dcc	Adds support for Distributed Checksum Clearinghouse (DCC)
dkim	Adds support for DomainKeys Identified Mail (DKIM)
dlfunc	Install local_scan.h header to compile separate dlfunc libraries
dmarc	Adds support for DMARC
dnsdb	Adds support for a DNS search for a record whose domain name is the supplied query
dovecot-sasl	Adds support for Dovecot's authentication
dsn	Adds support for Delivery Status Notifications (DSN)
exiscan-acl	Patch providing support for content scanning
lmtp	Adds support for lmtp
mbx	Adds support for UW's mbx format
pkcs11	Require pkcs11 support in net-libs/gnutls with USE=gnutls
prdr	Adds support for Per-Recipient Data Response
proxy	Add support for being behind a proxy, such as HAProxy
redis	Adds support for querying dev-db/redis
spf	Adds support for Sender Policy Framework
srs	Adds support for Sender Rewriting Scheme
tpda	Adds support for Transport Post-Delivery Actions

msmtp

daemon	Build/install msmtpd MTA daemon
mta	Enable this to install as system-wide MTA

netqmail

authcram	Enable AUTHCRAM support
gencertdaily	Generate SSL certificates daily instead of hourly
highvolume	Prepare netqmail for high volume servers

opensmtpd

mta	Enable this to install as system-wide MTA

postfix

dovecot-sasl	Enable net-mail/dovecot protocol version 1 (server only) SASL implementation
eai	Add support for SMTPUTF8
ldap-bind	Add support for binding to LDAP backend using dev-libs/cyrus-sasl
lmdb	Add support for using dev-db/lmdb for lookup tables
memcached	Add support for using net-misc/memcached for lookup tables
vda	Add support for virtual delivery agent quota enforcing

qmail-ldap

cluster	Enable this if you want to have cluster support in qmail-ldap
gencertdaily	Generate SSL certificates daily instead of hourly
highvolume	Prepare qmail for high volume servers
rfc2307	Add support for RFC2307 compliant uid/gid attributes
rfc822	Add support for RFC822 compliant mail attributes

qpsmtpd

postfix	create user with permissions for proper postfix interaction

ssmtp

mta	Install symlinks for sendmail-compatible MTA.

mate-base

caja

gtk3	Build with GTK+3 instead of GTK+2
mate	Install x11-themes/mate-icon-theme which is needed when this package is used in the MATE desktop environment.
packagekit	Enable support for installing via app-admin/packagekit based on mimetype

libmatekbd

gtk3	Build with GTK+3 instead of GTK+2

mate

base	Install base MATE Desktop applications that are recommended for the most common usage; for example, this installs the file manager. Disable this and other USE flags if you want a more minimal MATE Desktop.
extras	Install additional MATE Desktop applications that are recommended for extended usage of the MATE Desktop as upstream sees it; for example, this installs MATE Desktop's office related applications. Disable this if you plan to use your own non-MATE Desktop alternatives or a custom mixture of MATE and non-MATE packages.
gtk3	Build all of MATE DE with GTK+3 instead of GTK+2
help	Install gnome-extra/yelp to handle in application help menus and documentation browsing
notification	Force notification daemon to default to MATE's notification daemon. Enabled by default. Disable if it causes conflicts with other installed desktop environments.
themes	Install MATE Desktop's themes; if you use other themes, you can disable this to spare some space and time.

mate-applets

gtk3	Build with GTK+3 instead of GTK+2

mate-applets-meta

appindicator	Pull in mate-extra/mate-indicator-applet for AppIndicator applet
gtk3	Make sure applets are built with GTK+3 instead of GTK+2
netspeed	Pull in net-analyzer/mate-netspeed for net speed monitoring applet
sensors	Pull in mate-extra/mate-sensors-applet for hw sensors applet

mate-control-center

appindicator	Add support for AppIndicator
gtk3	Build with GTK+3 instead of GTK+2

mate-desktop

gtk3	Build with GTK+3 instead of GTK+2

mate-panel

gtk3	Build with GTK+3 instead of GTK+2

mate-session-manager

gtk3	Build with GTK+3 instead of GTK+2
xtrans	Build with Xtrans support; WARNING: Disabling this flag will result in ICE binding on all interfaces

mate-settings-daemon

gtk3	Build with GTK+3 instead of GTK+2

mate-extra

caja-extensions

cdr	Add an extension to burn files to cds using app-cdr/brasero.
gajim	Add an extension to support net-im/gajim.
gksu	Add an extension to support opening files as root with x11-libs/gksu.
gtk3	Build with GTK+3 instead of GTK+2
image-converter	Add image conversion support.
mail	Add an extension to support e-mail functionality.
open-terminal	Add an extension to support an open terminal.
pidgin	Add an extension to support net-im/pidgin
share	Add an extension to support sharing files.
wallpaper	Add an extension to support setting an image as the current wallpaper

mate-indicator-applet

gtk3	Build with GTK+3 instead of GTK+2

mate-media

gtk3	Build with GTK+3 instead of GTK+2

mate-netbook

gtk3	Build with GTK+3 instead of GTK+2

mate-polkit

accountsservice	Support extraction of data from AccountsService
appindicator	Add support for AppIndicator
gtk3	Build with GTK+3 instead of GTK+2

mate-power-manager

applet	Enable building of the MATE applet.
gtk3	Build with GTK+3 instead of GTK+2
man	Build power manager's man page.
pm-utils	Adds support for suspend/resume using sys-power/upower-pm-utils instead of sys-power/upower

mate-screensaver

consolekit	Enable support for sys-auth/consolekit
gtk3	Build with GTK+3 instead of GTK+2

mate-sensors-applet

gtk3	Build with GTK+3 instead of GTK+2

mate-system-monitor

gtk3	Build with GTK+3 instead of GTK+2

mate-user-share

gtk3	Build with GTK+3 instead of GTK+2

mate-utils

applet	Enable the mate dictionary applet
gtk3	Build with GTK+3 instead of GTK+2

media-fonts

corefonts

tahoma	Also install the Tahoma font. Due to the lack of a free bold variant, this may render badly. See bug 184790.

culmus

ancient	Install ancient semitic scripts
fancy	Install fancy fonts
fontforge	Use media-gfx/fontforge to build fonts from source
taamey	Install taamey fonts

dejavu

fontforge	Use media-gfx/fontforge to build fonts from source

fontawesome

otf	Install the OpenType version of the font
ttf	Install the TrueType version of the font

infinality-ultimate-meta

free	Install fonts for the "free" preset
latin	Install additional latin fonts
minimal	Install a minimal set of fonts
ms	Install (free) fonts for the "ms" preset

intlfonts

bdf	Installs BDF fonts in addition to PCF

liberation-fonts

fontforge	Use media-gfx/fontforge to build fonts from source

montecarlo

bdf	Install BDF fonts in addition to PCF

mplus-outline-fonts

ipafont	Generates new fonts merged with media-fonts/ja-ipafonts

sil-charis

compact	Use more compactly spaced font

sil-gentium

compact	Also install more compact version of the font.

terminus-font

a-like-o	Changes view of letter 'a' - a looks like o (see homepage)
center-tilde	Place the '~' character vertically centered on the line instead of to the top.
distinct-l	ll2 variant with more distinctive l (lowercase L)
pcf	Install Portable Compiled Font (PCF) (required for X11)
pcf-unicode-only	Remove non-unicode PCF fonts that could be problematic. See bug #520222.
psf	Install PC Screen Font (PSF) with unicode data (for linux console)
quote	Changes view of quotes: symmetric ` and ' instead of asymmetric one (see homepage)
ru-dv	Changes view of Russian letters 'de' and 've' (see homepage)
ru-g	Changes view of Russian letter 'ge' (see homepage)
ru-i	Changes view of Russian letter 'i' - not like Latin u, but like "mirrored" N (see homepage)
ru-k	Changes view of Russian letter 'k' (see homepage)

unifont

fontforge	Use media-gfx/fontforge to build fonts from source
utils	Install unifont utilities

media-gfx

album

plugins	Install optional plugins
themes	Install optional themes

alembic

boost	Use dev-libs/boost library
hdf5	Add support sci-libs/hdf5
pyalembic	Build pyalembic python bindings (needs dev-python/pyilmbase)
test	Build and run the test-suite
zlib	Use sys-libs/zlib for compressions

apngasm

7z	Enable support for 7zip compression
zopfli	Enable support for Zopfli compression

asymptote

boehm-gc	Enables using the Boehm-Demers-Weiser conservative garbage collector
offscreen	Enables off-screen rendering
sigsegv	Enables using dev-libs/libsigsegv

blender

boost	Enable features depending on boost.
bullet	Enable Bullet (Physics Engine).
collada	Add support for Collada interchange format through media-libs/opencollada.
colorio	Enable OpenColorIO color management through media-libs/opencolorio.
cuda	Build cycles renderer with nVidia CUDA support.
cycles	Build cycles renderer (requires media-libs/openimageio and dev-libs/boost).
dds	Adds DDS textures support to Blender.
doc	Build C and Python API documentation directly from the source code.
elbeem	Adds surface fluid simulation to Blender using El'Beem library.
game-engine	Adds Game Engine support to Blender.
headless	Build without graphical support (renderfarm, server mode only).
jemalloc	Use dev-libs/jemalloc for memory allocation.
llvm	Enable features depending on llvm.
man	Build and install man pages.
ndof	Enable NDOF input devices (SpaceNavigator and friends).
opencl	Allow OpenCL Graphics Acceleration. This may require extra graphics card drivers.
openimageio	Enable OpenImageIO Support
opennl	Enable use of Open Numerical Library
opensubdiv	Add rendering support form OpenSubdiv from Dreamworks Animation through media-libs/opensubdiv.
openvdb	Add GPU preview rendering. Only works with nVidia cards.
osl	Add support for OpenShadingLanguage scripting.
player	Build the Blender Player. THis requires the Game engine.
redcode	This flag add support for RED CODE camera digital format (5K HD images *.r3d) - EXPERIMENTAL.
test	Build the provided unit tests.
valgrind	Add support for memory debugging using dev-util/valgrind

comix

rar	Pulls app-arch/unrar for rar file support

cura

usb	Access 3D printers via USB

darktable

colord	Support color management using x11-misc/colord
flickr	Add support for uploading photos to flickr
geolocation	Enable geotagging support
kwallet	Enable encrypted storage of passwords with kde-frameworks/kwallet
opencl	Enable opencl support
pax_kernel	Triggers paxmarking of main darktable binary
webp	Enable WebP export support

digikam

addressbook	Enable akonadi contact integration
kipi	Enable support for media-plugins/kipi-plugins
lensfun	Enable support for media-libs/lensfun
marble	Enable support for geolocation using kde-apps/marble
mediaplayer	Enable support for media player using media-libs/qtav
panorama	Build the panorama plugin which requires media-gfx/hugin
semantic-desktop	Enable kde-frameworks/kfilemetadata support

eog-plugins

map	Enable world map display using media-libs/libchamplain
picasa	Enable uploading to Google's Picasa Web Albums

eom

gtk3	Build with GTK+3 instead of GTK+2

exact-image

swig	Adds Swig support dev-lang/swig

exiv2

webready	Support reading metadata over the internet

fbida

X	Install the Motif based image viewer "ida"
fbcon	Install the framebuffer image viewer "fbi"
ghostscript	Install the framebuffer ghostscript viewer "fbgs"
webp	Enable support for the WebP image format

fim

bmp	Enable BMP file support
dia	Enable DIA file support via app-office/dia
imagemagick	Use convert from media-gfx/imagemagick as fallback file opener
pcx	Enable PCX file support
xfig	Enable FIG file support via media-gfx/xfig

fontforge

truetype-debugger	Enable truetype debugger in fontforge

fotowall

webcam	Enable webcam support

freewrl

glew	Enable glew extensions
java	Build and install java EAI/SAI support library
libeai	Build EAI C library
opencl	Enable OpenCL support
osc	Allows for OSC-based control and communication between multiple freewrl instances
rbp	Enable support for Rigid Body Physics

geeqie

ffmpegthumbnailer	Enable video thumbnail support with media-video/ffmpegthumbnailer
gpu-accel	Enable GPU acceleration support - experimental
gtk3	Link against x11-libs/gtk+:3 instead of x11-libs/gtk+:2
map	Enable items map display - experimental

gimp

smp	Enable support for multiprocessors
vector-icons	Enable support for vector icons (experimental)

gmic

cli	Build CLI interface
opencv	Enable support for webcams using the OpenCV library

gnome-photos

flickr	Ensure runtime Flickr support

graphicsmagick

fpx	Enable FlashPix support with media-libs/libfpx
modules	Compile graphicsmagick with dynamically loadable modules
q16	Set storage quantum size to 16 (~2*memory)
q32	Set storage quantum size to 32 (~5*memory)
webp	Enable support for webp image format

graphviz

X	Builds lefty front-end, builds plugin -Txlib, and enables support for x11 in various other modules (needs cairo)
devil	Enables DevIL output plugin -Tdevil
gdk-pixbuf	Enables gdk-pixbuf2 plugin
gtk	Enables gtk+ output plugin -Tgtk (needs cairo)
gts	Enables support for gts
lasi	Enables PostScript output via media-libs/lasi, for plugin -Tlasi (needs cairo)

gthumb

colord	Use x11-misc/colord for color management
http	Enable webservice integration through net-libs/libsoup
json	Compile code that uses the libjson-glib library
slideshow	Enable slideshow plugin
webp	Enable support for webp image format

hugin

sift	automatically align images with media-gfx/autopano-sift-C

imagemagick

corefonts	Use media-fonts/corefonts which is required by some commands
fpx	Enable media-libs/libfpx support
hdri	Enable High Dynamic Range Images formats
heif	Enable support for ISO/IEC 23008-12:2017 HEIF/HEIC image format using media-libs/libheif
lqr	Enable experimental liquid rescale support using media-libs/liblqr
opencl	Enable OpenCL support
pango	Enable Pango support using x11-libs/pango
q32	Set quantum depth value to 32
q8	Set quantum depth value to 8
webp	Enable webp image format support using media-libs/libwebp

imageworsener

webp	enable webp image format support

inkscape

cdr	Enable support for CorelDRAW Diagrams
dia	pull in app-office/dia for dia import extension
inkjar	Enable support for OpenOffice.org SVG jar files
latex	pull in dependencies for LaTeX formulas
visio	Enable support for Microsoft Visio Diagrams
wpg	Enable support for WordPerfect Graphics

iscan-plugin-gt-f500

minimal	Install the firmware only, and not the plugin.

jpeg2ps

metric	Default to A4 paper size

kphotoalbum

kipi	Support for the KDE Image Plugin Interface
map	Enable map display support using kde-apps/libkgeomap

krita

color-management	Enable color management via media-libs/opencolorio
qtmedia	Enable sound support for animations via dev-qt/qtmultimedia
vc	Enable support for dev-libs/vc, could be a significant speed boost

librecad

3d	Require all 2D coordinates stored as 3D
tools	Build additional tool programs: tff2lff

luminance-hdr

fits	Enable support for the FITS format

mandelbulber

opencl	Enable GPU rendering support using OpenCL

nomacs

opencv	Build support for media-libs/opencv
zip	Build support for zip archives

nvidia-texture-tools

cg	Enable NVIDIA C graphics compiler toolkit plug-in
cuda	Enable NVIDIA CUDA toolkit support
glew	Enable support for The OpenGL Extension Wrangler Library (media-libs/glew)

openclipart

gzip	Compresses clip art using gzip

openexr_viewers

cg	Add support for nvidia's cg shaders

openvdb

abi3-compat	Disables newer features to maintain compatibility with ABI3. Enabled by default.
abi4-compat	Disables newer features to maintain compatibility with ABI4. Enabled by default.

photoqt

devil	Support additional image formats using media-libs/devil
exiv2	Use media-gfx/exiv2 as optional dependency
freeimage	Support additional iamge formats using media-libs/freeimage

pngcrush

system-libs	Use libpng and libz provided by system

potrace

metric	default to a4 paper size and metric measurement

povray

io-restrictions	POV-Ray's mechanism for control of I/O operations
mkl	Enable support for Intel Vector Math Library, part of sci-libs/mkl

pqiv

archive	Enable support for images in archives and cbX comic book files

pstoedit

emf	Enable media-libs/libemf support
flash	Enable media-libs/ming SWF support
pptx	Enable support for generating PowerPoint pptx files

qimgv

video	Add support for gif/webm playback via libmpv

qiv

magic	Use libmagic to determine mimetypes

sigal

s3	Enables support for the Amazon S3 service.

simple-scan

colord	Support color management using x11-misc/colord

slic3r

gui	Enable GUI

splashutils

fbcondecor	Support for the fbcondecor kernel patch.

ufraw

contrast	enable contrast setting option
fits	Enable support for the FITS image format through sci-libs/cfitsio
timezone	enable DST correction for file timestamps

xpaint

pgf	Support for loading PGF images

xsane

ocr	Enable support for Optical Character Recognition reader

yafaray

blender	Install addon for media-gfx/blender
fastmath	Enable mathematic approximations to make code faster
fasttrig	Enable trigonometric approximations to make code faster
opencv	Use media-libs/opencv

media-libs

a52dec

djbfft	Prefer D.J. Bernstein's library for fourier transforms

allegro

dumb	Enable media-libs/dumb module library support
opus	Enable Opus codec support
physfs	Enable physfs support
vga	Enables the VGA graphics driver

alsa-lib

alisp	Enable support for ALISP (ALSA LISP) interpreter for advanced features.
thread-safety	thread-safe API functions

alure

dumb	Enable media-libs/dumb module library support
fluidsynth	Enables Fluidsynth MIDI software synthesis

assimp

samples	Build viewer library
tools	Build assimp tool binary

aubio

double-precision	Compile in double precision mode.

avidemux-core

nvenc	Adds support for NVIDIA Encoder (NVENC) API for hardware accelerated encoding on NVIDIA cards.
system-ffmpeg	Use the ffmpeg provided by the system.

avidemux-plugins

aften	Enable A/52 (AC-3) audio encoder support.
amr	Enable Adaptive Multi-Rate format support via media-libs/opencore-amr.
dcaenc	Enable DTS Coherent Acoustics audio encoder support via media-sound/dcaenc.
fdk	Adds support for encoding AAC using media-libs/fdk-aac.
fribidi	Enable unicode bidirectional algorithm support via dev-libs/fribidi.
nvenc	Adds support for NVIDIA Encoder (NVENC) API for hardware accelerated encoding on NVIDIA cards.
opus	Adds support for the Opus codec via media-libs/opus.
twolame	Enable TwoLAME support via media-sound/twolame, an optimised MPEG Audio Layer 2 (MP2) encoder.
vpx	Enable WebM VP8 Codec SDK support via media-libs/libvpx.
x265	Enables HEVC support with media-libs/x265.

babl

cpu_flags_x86_f16c	Take advantage of CPU feature f16c

cal3d

16bit-indices	Enables use of 16bit indices

chromaprint

tools	Build and install fpcalc and fpcollect tools

clutter

egl	Enable EGL backend.
gtk	Use gdk-pixbuf from x11-libs/gtk+ as image rendering backend

cogl

gles2	Enable OpenGL ES 2.0 support
kms	Enable KMS support.
pango	Build cogl-pango library for x11-libs/pango integration

coin

qthelp	Build API documentation in QtHelp format
simage	Texture loading via media-libs/simage library

devil

allegro	Add support for Allegro
nvtt	Add support for media-gfx/nvidia-texture-tools

esdl

image	Enable image support

faad2

digitalradio	Digital Radio Mondiale (warning: disables other decoders)

flickcurl

raptor	Use media-libs/raptor for proper RDF serializing

fontconfig-infinality

nyx	Additional style using croscorefonts

freetype

adobe-cff	Use Adobe CFF as default font-renderer
bindist	Disable ClearType support (see http://freetype.org/patents.html)
bzip2	Support bzip2 compressed PCF fonts.
cleartype_hinting	New bytecode hinting mode for TrueType fonts that activates subpixel hinting (a.k.a. ClearType hinting) by default
fontforge	Install internal headers required for TrueType debugger in media-gfx/fontforge (built with USE=truetype-debugger)
harfbuzz	Use media-libs/harfbuzz for auto-hinting OpenType fonts. WARNING: may trigger circular dependencies!
infinality	Enable infinality options for improved LCD filtering
utils	Install utilities and examples from ft2demos

freeverb3

audacious	Build Audacious plugin
forcefpu	Disable assembly code
plugdouble	Build plugins in double precision mode (default is float)

ganv

fdgl	Use experimental force-directed graph layout

gd

webp	Enable support for the webp format

gegl

lensfun	Enable support for media-libs/lensfun.
umfpack	Enable sparse solving via sci-libs/umfpack.
webp	Enable support for media-libs/libwebp

giflib

rle	Build converters for RLE format (utah raster toolkit)

gmtk

dconf	Enable support for gnome-base/dconf

grilo

network	Enable network access for media discovery using net-libs/libsoup
playlist	Enable support for playlists through dev-libs/totem-pl-parser

gst-plugins-bad

bzip2	Enable bzip2 encoder/decoder plugin
egl	Enable EGL support
gles2	Enable GLES2 support

gst-plugins-base

X	Enable ximagesink and xvimagesink plugins; build GLX platform support if USE=opengl is enabled; build x11 windowing system support if USE=egl is enabled
egl	Enable EGL platform support
gbm	Enable Graphics Buffer Manager based EGL windowing system support (requires egl and at least one of gles or opengl)
gles2	Enable OpenGL library and plugin via GLESv2 API (requires egl)
ivorbis	Enable integer based vorbis decoder
opengl	Enable OpenGL library and plugin via desktop OpenGL API
pango	Enable pango GStreamer plugin
wayland	Enable Wayland EGL windowing system support (requires egl and at least one of gles2 or opengl)

gstreamer

orc	Disable some PaX memory protections to allow plugins that use dev-lang/orc for runtime optimization to be used on hardened PaX systems
unwind	Enable sys-libs/libunwind usage for better backtrace support in leaks tracer module

harfbuzz

glib	Compile with GLib Unicode support
graphite	Use graphite to render complex non-Roman writing systems

imlib2

shm	Use MIT shared memory support for X image transfer.

jbig2enc

webp	Add support for WEBP image format

leptonica

utils	Install command-line utilities
webp	Adds support for the WebP image format

libafterimage

shaping	Use MIT shaped X windows extention.
shm	Use MIT shared memory extention for X image transfer.

libass

harfbuzz	Enables OpenType shaping via media-libs/harfbuzz.

libbdplus

aacs	Add support for decryption of AACS

libbluray

aacs	Add support for decryption of AACS
bdplus	Use media-libs/libbdplus for BD+ decryption
java	Add support for BD-J
utils	Install command-line utilities and examples

libcanberra

alsa	Enables ALSA sound driver.
gstreamer	Enables gstreamer sound driver. Not useful when alsa or pulseaudio is available.
gtk	Enables building of gtk+ helper library, gtk+ runtime sound effects and the canberra-gtk-play utility. To enable the gtk+ sound effects add canberra-gtk-module to the colon separated list of modules in the GTK_MODULES environment variable.
gtk3	Enables building of gtk+3 helper library, gtk+3 runtime sound effects and the canberra-gtk-play utility. To enable the gtk+3 sound effects add canberra-gtk-module to the colon separated list of modules in the GTK_MODULES environment variable.
pulseaudio	Enables PulseAudio sound driver that should be able to support positional event sounds. This is the preferred choice for best sound events experience and picked by default if compiled in and possible to use at runtime.
sound	Install x11-themes/sound-theme-freedesktop to get sounds on Gnome and Xfce.
tdb	Enables Trivial Database support for caching purposes.

libextractor

apparmor	Enable apparmor support using sys-libs/libapparmor
archive	Enable archive support using app-arch/libarchive
gsf	Enable OLE2 (MS Office) plug-in support using gnome-extra/libgsf
magic	Enable magic support using sys-apps/file
midi	Enable MIDI support through media-libs/libsmf

libffado

test-programs	Install standalone test programs

libggi

vis	Enables sparc vis support for libggi

libgphoto2

serial	Enable serial port support

libgpod

gtk	Enable ArtworkDB support

libgroove

chromaprint	Enable audio fingerprinting using media-libs/chromaprint.
loudness	Enable loudness detection according to the EBU R128 standard using media-libs/libebur128.
sound	Enable audio playing.

liblastfm

fingerprint	Build the lastfm-fingerprint library

libmp4v2

utils	Install command-line utilities

libmypaint

gegl	Add support for media-libs/gegl

libomxil-bellagio

audioeffects	enable audio volume/mixer effects components
clocksrc	enable clock component
videoscheduler	enable xvideosink video scheduler

libopenglrecorder

openh264	Enable H.264 support using media-libs/openh264
vpx	Enable VP8/VP9 codec support via media-libs/libvpx

libpagemaker

tools	Build command line file format conversion tools

libpng

apng	support unofficial APNG (Animated PNG) spec

libpostproc

pic	Force shared libraries to be built as PIC (this is slower).

libquicktime

schroedinger	Enable Dirac video support (an advanced royalty-free video compression format) via libschroedinger (high-speed implementation in C of the Dirac codec)

libraw

demosaic	Enable support for external interpolation algorithms

libsdl

joystick	Control joystick support (disable at your own risk)
sound	Control audio support (disable at your own risk)
tslib	Build with tslib support for touchscreen devices
video	Control video support (disable at your own risk)

libsdl2

gles	include OpenGL ES support
haptic	Enable the haptic (force feedback) subsystem
joystick	Control joystick support (disable at your own risk)
kms	Build the KMSDRM video driver
sound	Control audio support (disable at your own risk)
tslib	Build with tslib support for touchscreen devices
video	Control video support (disable at your own risk)

libvisio

tools	Build conversion tools

libvpx

highbitdepth	Enable 10 and 12 bit support for VP9.
postproc	Enable additional post processing filters
svc	Enable spatial-svc support (experimental)

libwebp

experimental	Build with -DWEBP_EXPERIMENTAL_FEATURES
swap-16bit-csp	Enable byte swapping for 16 bit colorspace

libyami

dmabuf	Enable dma_buf buffer sharing.
egl	Enable EGL support.
md5	Add support for generating md5 sums for each frame.
v4l	Add support for V4L2 hardware codecs.

libzmf

tools	Build conversion tools

lilv

dyn-manifest	Add LV2 Dynamic Manifest support. See http://lv2plug.in/ns/ext/dynmanifest/

lv2

plugins	Enables examples plugins.

lvtk

gtk2	Enable x11-libs/gtk+:2 based GUI support
tools	Compile and install ttl2c tool

mediastreamer

amr	Use of AMR Narrow Band codec plugin
filters	Enable compilation of filters
g726	Support g726 codec
g729	Use g726 codec plugin
ilbc	Use of iLBC (RFC3951) codec plugin
ntp-timestamp	Turn on NTP timestamping on received packet
opus	Enable opus codec support
ortp	Enable usage of net-libs/ortp
pcap	Enable usage of net-libs/libpcap
silk	Use silk (skype protocol) codec plugin
video	Enable video support

mesa

bindist	Disable patent-encumbered ARB_texture_float, EXT_texture_shared_exponent, and EXT_packed_float extensions.
classic	Build drivers based on the classic architecture.
d3d9	Enable Direct 3D9 API through Nine state tracker. Can be used together with patched wine.
dri3	Enable DRI3 support.
egl	Enable EGL support.
gallium	Build drivers based on Gallium3D, the new architecture for 3D graphics drivers.
gbm	Enable the Graphics Buffer Manager for EGL on KMS.
gles1	Enable GLESv1 support.
gles2	Enable GLESv2 support.
llvm	Enable LLVM backend for Gallium3D.
opencl	Enable the Clover Gallium OpenCL state tracker.
openmax	Enable OpenMAX video decode/encode acceleration for Gallium3D.
osmesa	Build the Mesa library for off-screen rendering.
pax_kernel	Enable if the user plans to run the package under a pax enabled hardened kernel
pic	disable optimized assembly code that is not PIC friendly
unwind	Add support for stack trace unwinding and function name resolution
valgrind	Compile in valgrind memory hints
vdpau	Enable the VDPAU acceleration interface for the Gallium3D Video Layer.
vulkan	Enable Vulkan drivers
wayland	Enable support for dev-libs/wayland
xa	Enable the XA (X Acceleration) API for Gallium3D.
xvmc	Enable the XvMC acceleration interface for the Gallium3D Video Layer.

mlt

compressed-lumas	Compress the luma files in png.
frei0r	Build the module for media-plugins/frei0r-plugins
kdenlive	Build support for kde-apps/kdenlive
lua	Build SWIG bindings for Lua
melt	Build the melt commandline tool
opencv	Build motion tracking module using media-libs/opencv
python	Build SWIG bindings for Python
rtaudio	Builds rtaudio consumer for native audio support on multiple platforms.
ruby	Build SWIG bindings for Ruby

netpbm

rle	Build converters for the RLE format (utah raster toolkit)

opencv

contrib	Install user contributed scripts from opencv_contrib (Experimental!)
contrib_cvv	CVV module requires Qt5
contrib_dnn	DNN module contrib requires tiny dnn
contrib_hdf	HDF module requires sci-libs/hdf5
contrib_sfm	SFM module requires eigen, gflags, and glog
contrib_xfeatures2d	Enables xfeatures2d and autodownload of samples in contrib
cuda	Enable NVIDIA Cuda computations support (Experimental!)
dnn_samples	Download dnn caffeemodel samples
eigen	Enable usage of dev-cpp/eigen for computations
gdal	Enable support for sci-libs/gdal library
gflags	Use Google's C++ argument parsing library
glog	Use Google's C++ loggin library
opencl	Add support for OpenCL
tesseract	Use Google's OCR Engine
testprograms	Build and install programs for testing OpenCV (performance)
vtk	Build new 3D visualization module viz based on sci-libs/vtk
webp	Enable support for webp image format

openh264

plugin	Install the Gecko Media Plugin (GMP) for use with Mozilla packages
utils	Install the CLI encoder and decoder utilities

openimageio

colorio	Use media-libs/opencolorio
cpu_flags_x86_avx512f	SIMD Optimization
cpu_flags_x86_f16c	SIMD Optimization
field3d	Use media-libs/Field3D
opencv	Use media-libs/opencv
ptex	Use media-libs/ptex

opensubdiv

cuda	Enable NVIDIA CUDA Toolkit support through dev-util/nvidia-cuda-toolkit.
opencl	Enable OpenCL support through virtual/opencl.
ptex	Adds support for faster per-face texture mapping through media-libs/ptex.
tbb	Enable multithreading with the Intel Threads Building Blocks through dev-cpp/tbb.

opus

ambisonics	Enable ambisonics support (experimental).
custom-modes	Build with custom-modes.

opusfile

fixed-point	Enable fixed-point arithmetic operations
float	Enable floating point arithmetic operations
http	Enable http connections

osl

cpu_flags_x86_avx512f	SIMD Optimization
cpu_flags_x86_f16c	SIMD Optimization
partio	Use media-libs/partio

phonon

designer	Install plugin for dev-qt/designer
vlc	Install VLC Phonon backend

phonon-gstreamer

network	Enable network streaming support via libsoup

portmidi

test-programs	Install various example programs

qtav

gui	Build a video player gui

quvi

json	Enable support for JSON output

raptor

json	Enable support for JSON parsing

raspberrypi-userland-bin

hardfp	Use armv6 hardfp ABI

sdif

ftruncate	Enables usage of ftruncate v. truncate

sdl-image

webp	support loading WEBP images

sdl-mixer

fluidsynth	Use media-sound/fluidsynth for MIDI support
midi	basic support for MIDI files
mod	basic support for MOD files
playtools	Install playwave and playmus tools (useful for testing)
smpeg	Use media-libs/smpeg for MP3 support
wav	support WAVE files

sdl-sound

physfs	Enable physfs support

sdl2-image

webp	support loading WEBP images

sdl2-mixer

fluidsynth	Use media-sound/fluidsynth for MIDI support
midi	basic support for MIDI files
mod	basic support for MOD files
playtools	Install playwave and playmus tools (useful for testing)
smpeg	Use media-libs/smpeg for MP3 support
tremor	enable OGG Vorbis music via libtremor
wav	support WAVE files

sge

image	enable sdl-image support

spandsp

fixed-point	Enable fixed point support

speex

utils	Enables speex commandline utilities (speexenc, speexdec).
vbr	Enable VBR support.

svgalib

kernel-helper	Build the helper kernel module

taglib

boost	Use dev-libs/boost instead of GCC built-ins

tremor

low-accuracy	enable 32bit only multiply operations

urt

tools	Install tools

vigra

valgrind	Enable valgrind in make check

vulkan-loader

layers	Include the vulkan layers

waffle

egl	Enable EGL support
gbm	Enable support for the Generic Buffer Manager (gbm)
wayland	Enable Wayland support

x264

10bit	Set output bit depth to 10, this may not be compatible with all decoders
interlaced	enable interlaced encoding support, this can decrease encoding speed by up to 2%
opencl	Add support for OpenCL.
pic	disable optimized assembly code that is not PIC friendly

x265

10bit	Add support for producing 10bits HEVC.
12bit	Add support for producing 12bits HEVC.
numa	Build with support for NUMA nodes.
pic	Disable optimized assembly code that is not PIC friendly
power8	Enable support for Power 8 assembly optimizations.

xine-lib

bluray	Enable playback of Blu-ray filesystems using media-libs/libbluray
dxr3	Enable support for DXR3 mpeg acceleration cards.
flac	Build the media-libs/flac based FLAC demuxer and decoder. This flag is not needed for playing FLAC content, neither standalone nor in Ogg container (OggFLAC), but might have better support for exotic features like 24-bit samples or 96kHz sample rates.
gtk	Build the gdkpixbuf-based image decoder plugin.
imagemagick	Build the ImageMagick-based image decoder plugin.
mad	Build the media-libs/libmad based mp3 decoder. This mp3 decoder has superior support compared to the one coming from FFmpeg that is used as a fallback. If you experience any bad behaviour with mp3 files (skipping, distorted sound) make sure you enabled this USE flag.
mmap	Use mmap() function while reading file from local disks. Using mmap() will use more virtual memory space, but leaves to the Kernel the task of caching the file's data. mmap() access should be faster, but might misbehave if the device where the file resides in is removed during playback.
truetype	Use media-libs/freetype for font rendering and media-libs/fontconfig for font discovery. Enabling this USE flag will allow OSD (such as subtitles) to use more advanced font and to more easily select which font to use. The support for TrueType fonts in xine-lib is still experimental, and might not be as good looking as the bitmap fonts used with this USE flag disabled.
vdr	Build the VDR plugin
vidix	Enable support for vidix video output.
vis	Adds support for SIMD optimizations for UltraSPARC processors.
vpx	Enable VP8 codec support via media-libs/libvpx.
xvmc	Enable support for XVideo Motion Compensation (accelerated mpeg playback).

xvid

pic	disable optimized assembly code that is not PIC friendly

media-plugins

alsa-plugins

arcam_av	Enables Arcam AV control plugin
mix	Enables upmix and vdownmix plugin
usb_stream	Enables usb_stream plugin

audacious-plugins

adplug	Build with AdPlug (Adlib sound card emulation) support
ampache	Support controlling audacious via www-apps/ampache
aosd	Enable support for Audacious OSD
bs2b	Enable Bauer Bauer stereophonic-to-binaural headphone filter
cue	Support CUE sheets using the libcue library
fluidsynth	Support FluidSynth as MIDI synth backend
gme	Support various gaming console music formats
gtk3	Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)
hotkeys	Enable support for controlling via hotkeys
http	Support HTTP streams through neon
scrobbler	Build with scrobbler/LastFM submission support
sid	Build with SID (Commodore 64 Audio) support
soxr	Build with SoX Resampler support
speedpitch	Enable speed/pitch effects

calf

experimental	Enable experimental features/plugins
lv2	Add support for Ladspa V2

frei0r-plugins

facedetect	Enables building of facedetect plugin, which depends on media-libs/opencv
scale0tilt	Enables building of scale0tilt and vectorscope plugins, which depend on media-libs/gavl

gkrellmpc

threads	Use separate thread to init connection (unsafe)

grilo-plugins

chromaprint	Enable Chromaprint support
daap	Enable dmap support through net-libs/libdmapsharing
flickr	Enable Flickr support
freebox	Build support for viewing TV channels using Freebox
gnome-online-accounts	Enable net-libs/gnome-online-accounts support
subtitles	Enables support for subtitle from OpenSubtitles
thetvdb	Build support for thetvdb.com
tracker	Build support for content discovery using the app-misc/tracker indexer
vimeo	Build support for Vimeo content discovery using net-libs/libsoup and dev-libs/libgcrypt
youtube	Build support for YouTube content discovery using dev-libs/libgdata

gst-plugins-gl

libvisual	Enable visualization effects via media-libs/libvisual

gst-plugins-gtk

egl	Enable EGL platform usage
gles2	Enable gtkglsink OpenGL sink based on GLESv2 API
opengl	Enable gtkglsink OpenGL sink based on desktop OpenGL API

gst-plugins-meta

http	Enable http streaming via net-libs/libsoup
libvisual	Enable visualization effects via media-libs/libvisual
opus	Enable Opus audio codec support
vpx	Enables vp8 codec support using libvpx, required to play some HTML5 videos

gst-plugins-vaapi

drm	Enable DRM renderer
egl	Enable EGL support
gles2	Enable GLESv2 and GLESv3 support

hexter

gtk2	Enable x11-libs/gtk+:2 based GUI

imlib2_loaders

eet	Enable Eet image loader
xcf	Enable XCF image loader

kipi-plugins

flashexport	Build the flash export plugin
mediawiki	Build the mediawiki export plugin
remotestorage	Build plugin for remote storage using network protocols such as FTP, SSH, SAMBA via kde-frameworks/kio
vkontakte	Build plugin for vkontakte.ru

mediastreamer-ilbc

20ms-frames	enable 20ms frame size (default is 30ms). Some VOIP providers such as Gizmo5 (aka Sipphone) require the codec to be compiled with the 30ms setting.

mythplugins

cdr	Allows MythMusic to burn CD-Rs
exif	Allows MythGallery to read EXIF data from photos
fftw	Adds visual effects to MythMusic when playing back music
hls	HTTP Live Streaming support
mytharchive	Allows you to archive recorded content to CD or DVD
mythbrowser	Adds a web browser within MythTV
mythgallery	Adds a picture viewing gallery within MythTV
mythgame	Adds a frontend to various ROM emulators within MythTV
mythmusic	Adds the ability for MythTV to act as a music player
mythnetvision	Adds the ability to view netvision devices within MythTV
mythnews	Adds a news viewer within MythTV
mythweather	Adds weather information within MythTV
mythzoneminder	Adds support for zoneminder (requires a server with the appropriate mythtv daemon somewhere on the network).
raw	Allows MythGallery to view photos saved in RAW format

vdr-burn

dvdarchive	DMH DVD - Archive

vdr-dvbapi

dvbcsa	use media-libs/libdvbcsa free implementation of the DVB Common Scrambling Algorithm

vdr-epgsearch

conflictcheckonly	install the "conflictcheckonly" vdr-plugin
epgsearchonly	install the "epgsearchonly" vdr-plugin
quicksearch	install the "quicksearch" vdr-plugin
tre	Add support for unlimited fuzzy searching with help of dev-libs/tre library

vdr-pvr350

yaepg	Enables full support for the output format of vdr-yaepg

vdr-streamdev

client	Compile the VDR plugin vdr-streamdev-client that acts like a dvb-budget card
server	Compile the VDR plugin vdr-streamdev-server that allows remote systems to access the DVB cards used for the local VDR

vdr-text2skin

contrib	Install user contributed scripts

vdr-vdrmanager

stream	Add support for streaming Video to Android client

vdr-weatherng

dxr3	enables lower osd color depth for dxr3 cards

vdr-xine

yaepg	Enables support for the plugin vdr-yaepg (showing scaled video besides OSD)

vdr-xineliboutput

bluray	Enable BluRay metadata support through media-libs/libbluray
cec	Enable CEC support through dev-libs/libcec
libextractor	Use media-libs/libextractor to gather files' metadata in media-player
vdr	Compile the vdr output plugin to use local or remote xine as output
xine	Compile the xine input plugin for displaying vdr video and OSD

media-radio

ax25-tools

X	Enable some X based configuration tools.

fldigi

hamlib	Enables support by the Hamlib amateur radio rig control library to get/set frequency and mode of the ham radio in use

tucnak

hamlib	Enables support by the Hamlib amateur radio rig control library to get/set frequency and mode of the ham radio

unixcw

ncurses	Enables building the curses based morse code tutor program 'cwcp'.

xastir

festival	Enable text to speech synthesizer
gdal	Support for some further map formats
geotiff	Install geotiff support. Allows using USGS DRG topo maps or other types of geotiff mapes/images

media-sound

abcde

id3tag	Support ID3, ID3v2 tagging of audio files
mac	Enable support for Monkey's Audio files
normalize	Add support for normalizing audio file volume levels
opus	Support opus encoding using opusenc
replaygain	Support for Replay Gain metadata, for relative volume adjustment

abcm2ps

pango	Use the pango library to render fonts with non-latin characters

alsa-utils

bat	install basic audio tester (BAT) util
libsamplerate	install utils that use libsamplerate (e.g. alsaloop)
ncurses	install utils that use ncurses (e.g. alsamixer)

alsaplayer

id3tag	Enables ID3 tagging with id3tag library

amsynth

dssi	Enable support for DSSI Soft Synth Interface

apulse

pa-headers	Install PulseAudio headers

aqualung

ifp	Enable support for iRiver iFP portable audio players
lua	Enable support for programmable title formatting with dev-lang/lua
mac	Enable support for decoding Monkey's Audio files
podcast	Enable podcast support
systray	Enable system tray support

ario

audioscrobbler	Enable song tracking via last.fm
idle	Enable experimental support for MPD's idle command to reduce bandwidth and cpu usage, requires MPD 0.14

asunder

mac	Support for creation of Monkey's Audio files (APE)
opus	Support for creation of Opus files

audacious

gtk3	Link against version 3 of the GIMP Toolkit instead of version 2 (x11-libs/gtk+)

audacity

id3tag	Enables ID3 tagging with id3tag library
lv2	Add support for Ladspa V2
midi	Enables MIDI support
portmixer	Enable the internal portmixer feature
sbsms	Enables sbsms library support for slower, more accurate pitch and tempo changing
soundtouch	Enables soundtouch library support for pitch and tempo changing