equery uses pam
[ Searching for packages matching pam... ]
[ 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 sys-libs/pam-0.99.7.1 ]
 U I
 - - elibc_FreeBSD : <unknown>
 + + nls           : Adds Native Language Support (using gettext - GNU locale utilities)
 - - selinux       : !!internal use only!! Security Enhanced Linux support, this must be set by the selinux profile or breakage will occur
 - - vim-syntax    : Pulls in related vim syntax scripts.