perl inside batch files?

I don't program batch files much anymore, so I know that this is old
hat to most of you (well, maybe all of you).

I have come across a few batch files that contain perl scripts. I'm
not a perl expert, and back in the golden days of dos 1.0, we didn't
have perl scripts inside the batch file. So, I haven't any idea on
what they do or how to change them :)

Any pointers on where to find some decent documentation on how Windows
XP handles Perl scripts? The Windows documentation doesn't seem to
even address it, and the stuff on deja is way out of date (at least it
seems to be). So, I'd appreciate some help...

In particular, any guidance on what is processed by windows and what is
processed as a perl script? How does the batch processor know which is
which?

Regards, Brad