my $exp = $line =~ m/[FAR PASCAL|FAR PASCAL_CONV] (.*)/gi;

##</code><code>##

$line =~ m/(?:FAR PASCAL(?:_CONV)?) (.*)/i;

##</code><code>##

$line = "FAR PASCAL_CONV blurb";
my ($expr) = $line =~ m/(?:FAR PASCAL(?:_CONV)?) (.*)/i;

# $expr now contains "blurb";