Format:
                     - comment lines begin with # (no inline comments)
                     - one DEPEND atom per line followed by additional KEYWORDS
                     - lines without any KEYWORDS imply unstable host arch

                     Example:
                     # always use unstable libgd
                     media-libs/libgd ~x86
                     # only use stable mplayer
                     media-video/mplayer -~x86
                     # always use unstable netcat
                     net-analyzer/netcat