#!/usr/bin/env perl
use strict;
use warnings;



my $p = '
AAA
//content
:AAA

';

if (
$p =~ /

(?(R)
    (?P<tag>ZZZ)             
|
    (?P<tag>AAA)
)

[^:]+

:(?P=tag)

/mx

){	
	print "ok\n";	
}
else{
	print "oops\n";
}