atma@beast ~ $ equery uses irssi    
[ Searching for packages matching irssi... ]
[ Colour Code : set unset ]
[ Legend        : Left column  (U) - USE flags from make.conf                     ]
[                  : Right column (I) - USE flags packages was installed with ]
[ Found these USE variables for net-irc/irssi-0.8.10 ]
 U I
 - - ipv6    : Adds support for IP version 6
 - - minimal : Install a very minimal build (disables, for example, plugins, fonts, most drivers, non-critical features)
 - - perl    : Adds support/bindings for the Perl language.
 - - socks5  : Adds support for the socks5 proxy
 + + ssl     : Adds support for Secure Socket Layer connections