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

my ( @l1, 
     @l2 ); 

@l1 = qw(Date IndexID Maturity OnTheRun CompositePrice 
CompositeSpread ModelPrice ModelSpread Depth Heat);

@l2 = qw(OnTheRun CompositePrice CompositeSpread Depth);

# More code here...