Can pg_trgm handle non-alphanumeric characters?

Hello,

This question may be appropriate for pgsql-general, but let me ask here 
because the only relevant discussion seems to have been done on 
pgsql-hackers:

http://archives.postgresql.org/pgsql-hackers/2011-09/msg00169.php

Can pg_trgm support non-alphanumeric characters by undefining KEEPONLYALNUM 
in contrib/pg_trgm/trgm.h? If no, what kind of problems would happen?

Regards
MauMau