#!/usr/bin/perl
while(<DATA>){
if (/^({\w+})/) {
$f = $1;
}

if ($f =~ m/({NEW}|{OLD})/ ) {
print $_;
}

}

__DATA__
{NEW}
Hi How
r u <
I am
doing
fine <
{OLD}
Hi How
r u <
{OLDAGE}