c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"print 'Perl version ', $];
 ;;
 my $s = 'abcd';
 ;;
 local our @caps;
 ()= $s =~ m{ (?= (\w\w) (?{ push @caps, [ $^N, $-[1] ] })) }xmsg;
 dd \@caps;
 ;;
 my $skip;
 print qq{captured '$_->[0]' at offset $_->[1]}
   for grep $skip = !$skip, @caps;
"
Perl version 5.008009
[["ab", 0], ["ab", 0], ["bc", 1], ["bc", 1], ["cd", 2], ["cd", 2]]

captured 'ab' at offset 0
captured 'bc' at offset 1
captured 'cd' at offset 2