- "assume-digests", "binpkg-logs", "buildpkg", "buildsyspkg", "candy",
- "ccache", "cgroup", "chflags", "clean-logs",
- "collision-protect", "compress-build-logs", "compressdebug",
- "compress-index", "config-protect-if-modified",
- "digest", "distcc", "distcc-pump", "distlocks",
- "downgrade-backup", "ebuild-locks", "fakeroot",
- "fail-clean", "force-mirror", "force-prefix", "getbinpkg",
- "installsources", "ipc-sandbox",
- "keeptemp", "keepwork", "fixlafiles", "lmirror",
- "merge-sync",
- "metadata-transfer", "mirror", "multilib-strict",
- "network-sandbox", "news",
- "noauto", "noclean", "nodoc", "noinfo", "noman",
- "nostrip", "notitles", "parallel-fetch", "parallel-install",
- "prelink-checksums", "preserve-libs",
- "protect-owned", "python-trace", "sandbox",
- "selinux", "sesandbox", "sfperms",
- "sign", "skiprocheck", "split-elog", "split-log", "splitdebug",
- "strict", "stricter", "suidctl", "test", "test-fail-continue",
- "unknown-features-filter", "unknown-features-warn",
- "unmerge-backup",
- "unmerge-logs", "unmerge-orphans", "userfetch", "userpriv",
- "usersandbox", "usersync", "webrsync-gpg", "xattr"])