warn 'tab' if unescape("\\t")  eq "\t";
   warn 'nl'  if unescape("\\n")  eq "\n";
   warn 'bel' if unescape("\\07") eq "\07";

   sub unescape
   {
      my($s)=@_;

      $s =~ s/(\\[^\d])/ (eval "\"$1\"") || $1 /ge;  # "\t", "\n", etc
      $s =~ s/\\(0\d+)/ eval "chr($1)"         /ge;  # "\07", etc.

      return $s;
   }