#!/usr/bin/perl

use strict;

local $/ = '{IT}';

while (my $line = <DATA>) {
    my ($it) = $line =~ /(^\s\d+)/;
    print "{IT}$it\n"
      if ! ( $line =~ /{LINE}/
             && $line =~ /{IT}/ )
             && ( defined( $it) );
}
__DATA__
{IT} 343
1
{DATE}
090104
{LINE}
LEGISLATORS  VISIT SENIOR APARTMENT COMPLEX
{TAG}
1lutherridge0104.ART
{ID}
234
{IT} 434
2
{DATE}
090104
{LINE}
LEGISLATORS  VISIT SENIOR APARTMENT COMPLEX