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

print STDERR "STDERR oops\n";
print STERR "STERR oops\n";

##</code><code>##

Name "main::STERR" used only once: possible typo at ./z8a line 7.
STDERR oops
print() on unopened filehandle STERR at ./z8a line 7.