Curiosity: Perl File Extension in Emacs Config

[Xah Lee]

A curiosity question.

emacs's “auto-mode-alist” has this value:

("\\.\\([pP]\\([Llm]\\|erl\\|od\\)\\|al\\)\\'" . perl-mode)
the regex there seems a bit wild. If i didn't get it wrong, then its like this

. ([pP] ( [Llm] | erl | od ) | al )
so it covers:

.pl
.perl
.pod
.pm
.al
plus SOME case variations. e.g. {.pL , .PL}.

what's the “.al” for?

is it necessary to include the “.pod”? because the perl-mode doesn't do any 
coloring with “.pod” files, nor cperl-mode. If there's a mode handing “.pod” 
file am guessing it won't be perl-mode.

also, is the “.perl” there necessary? Is that a accepted perl file suffix? 
(Just checked it's not in any file bundled with perl v5.10.1.)

would it be better if it's just

("\\.\\(p\\([lm]\\)\\)\\'" . perl-mode)

?

 Xah