$ perl -Mstrict -Mwarnings -E '
my $x = q{L,0010,8001149805,003,20121015,0600,267,204193,20121015,1300,,GBFER,204193};
my $y = q{L,0010,8001149805,003,20121015,0600,267,204193,20121015,1300,,XXXXX,204193};
if (! ($x =~ /(?:GBFER|GBFOO)/)) { say "match" } else { say "no match" }
if (! ($y =~ /(?:GBFER|GBFOO)/)) { say "match" } else { say "no match" }
'
no match
match