From 'man perlfaq1':

What's the difference between ""perl"" and ""Perl""?

One bit.  Oh, you weren't talking ASCII? :-) Larry now uses "Perl" to 
+signify
the language proper and "perl" the implementation of it, i.e. the curr
+ent
interpreter.  Hence Tom's quip that "Nothing but perl can parse Perl."
+  You
may or may not choose to follow this usage.

[...]

But never write "PERL", because perl isn't really an acronym, aprocryp
+hal
folklore and post-facto expansions notwithstanding.
[download]

I don't mean to be a smart-ass, but I noticed you used "PERL" in your other
two other posts today as well.

-- ar0n | Just Another Perl Joe