my %map = ();

while (<IN>) {
	chomp $_;
	my @items = split(/\,/, $_);
	$map{$items[0]} = $items[1]; # [1] not [2]
}
close IN;

my ($cur_awb,$cur_val);

while (<BASE>) {
	chomp $_;

	if ($_ =~ m/\<KEY_BOL_REF\>(\d*)\<\/KEY_BOL_REF\>/) {
		$cur_awb = $1;
		$cur_val = $map{$cur_awb}; # should do some error check here
		print OUT $_ . "\n";
	}
	# ... etc.
}