Note that these flags are named using the ISO3166-1 alpha-2 country
codes where appropriate. A list of codes can be found at
http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2

There are many packages contain flags, see apt-file flag, but none of
them was adapted to use it outside project (as a depend), this is the
first such package. I'll open discussion in debian-devel@ where flags
can be placed, for the present I have placed them into
/usr/share/flags/countries.