After a match against some variable $var:

$` is the same as substr($var, 0, $-[0])
$& is the same as substr($var, $-[0], $+[0] - $-[0])
$' is the same as substr($var, $+[0])
$1 is the same as substr($var, $-[1], $+[1] - $-[1])
$2 is the same as substr($var, $-[2], $+[2] - $-[2])
$3 is the same as substr $var, $-[3], $+[3] - $-[3])

##</code><code>##

use strict;
for	my $regex (qr/(.)oo(.)ar(.)az/, qr/fo(.)barba(.)/) {
	my $str = "foobarbaz";
	$str =~ s/$regex/
		my @a;
		for my $index (1 .. $#+) {
			push @a, substr($str, $-[$index], $+[$index] - $-[$index]);
		}
		join "," , @a;
	/e;
	print "$str\n";
}

##</code><code>##

f,b,b
o,z