#!/usr/bin/perl -w
use strict;

my $good= "OK";
my $bad;

print <<"HTML";
   This block is $good.
HTML

print <<"HTML";
   This block is $bad.
HTML
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The first print won't give you a warning and the second one will. The line number reported in the warning is the line number of the statement. If the statement covers more than one line, then warnings on different lines but in the same statement will report the same line number.

So it is some undefined value in the body of your heredoc that is causing the warning.

        - tye (but my friends call me "Tye")