doc - Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
ldap - Add LDAP support (Lightweight Directory Access Protocol)
nls - Add Native Language Support (using gettext - GNU locale utilities)
readline - Enable support for libreadline, a GNU line-editing library that almost everyone wants
selinux - !!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
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.
ssl - Add support for SSL/TLS connections (Secure Socket Layer / Transport Layer Security)
test - Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)
tofu - Enable support for Trust on First use trust model; requires dev-db/sqlite.
tools - Install extra tools (including gpgsplit and gpg-zip).
tpm - Enable TPM support via app-crypt/tpm2-tss and build tpm2d.
usb - Build direct CCID access for scdaemon; requires dev-libs/libusb.
user-socket - try a socket directory which is not removed by init manager at session end
verify-sig - Verify upstream signatures on distfiles
