c:\@Work\Perl\monks>perl -wMstrict -le
"$_ = 'no joy';
 ;;
 my $output = '';
 while($_ =~ /\A([S\-\+XIO]+)\z/g)
 {
     my $part = $1;
     $output = $output . $part;
 }
 print qq{final output: '$output'};
"
final output: ''