If you treat the arg as a regex pattern, "[P/R]" actually means "P", "/" or "R". You simply want "[PR]".

"." means any character

"[QRG]" will match one of those three characters.

And if you want to format you specified: 

my $pat = '';
for ($ARGV[0]) {
   /\G ([A-EG-WYZ]+)            /xgc && do { $pat .= $1;       redo };
   /\G X                        /xgc && do { $pat .= '.';      redo };
   /\G F                        /xgc && do { $pat .= '[QRG]';  redo };
   /\G \[ ([A-Z]) \/ ([A-Z]) \] /xgc && do { $pat .= "[$1$2]"; redo };
   /\G \z                       /xgc && last;

   my $pos  = pos();
   my $next = substr($_, $pos, 1);
   die("Unrecognized character \"$next\" at pos $pos\n");
}

[download]

Update: Added missing /xgc.

In reply to Re: Searchin' through values by ikegami
in thread Searchin' through values by MaroonBalloon

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