(id bsd)
(description "An operating system in the BSD Unix family")

(id darwin)
(description "Darwin-based (Apple macOS X, iOS) operating system")

(id dragonfly)
(description "The DragonFlyBSD operating system")

(id freebsd)
(description "The FreeBSD operating system")

(id gnu-linux)
(description "A GNU/Linux distribution")

(id netbsd)
(description "The NetBSD operating system")

(id openbsd)
(description "The OpenBSD operating system")

(id posix)
(description "This implementation is running on a POSIX system")

(id solaris)
(description "The Solaris/SunOS operating system")

(id unix)
(description "Unix-like operating system")

(id windows)
(description "Microsoft Windows operating system")