#!/usr/bin/perl
open(FILE1, $ARGV[0]) || die "Error: $!\n";
@lines = <FILE1>;

while ($line=<FILE1>){
if ($line=~/^BEGIN_TAG/){
	<FILE1>; #get next line
	if ($line=~/^X1/ .. /^X2/){ # get all between X1 and X2
		
		print $line; # print all of it 
		
	}
}
}