warnings::warn using only standard warnings categories?

Can /warnings::warn/   be used with only standard warnings categories 
(not a module-custom cat)?

warnings::warn() dies unless warnings::register() was previously called, 
but if the package does not wish to create any new warnings categories 
then warnings::register should not be used, I assume.

|#!/usr/bin/env perl||
||
||package Foo;||
||sub import {||
||  use Carp;||
||  use warnings;||
||  my $enabled = warnings::enabled("deprecated");||
||
||  warnings::warn "This is deprecated" if $enabled; #dies with "package 
'Foo' not registered for warnings"||||
||}||
||
||package main;||
||
||use warnings FATAL => 'all';||
||Foo->import("blah");||
||die "SHOULD NOT GET HERE (due to FATAL => all)";||
|

• warnings::warn using only standard warnings categories? by Jim Avera
• Re: warnings::warn using only standard warnings categories? by Arne Johannessen via perl5-porters