[Crypt::SSLeay] Client Cert Support?

[Robin Darby]

Hello,
	Can anyone tell me what 'CLIENT CERT SUPPORT', as in:
  # CLIENT CERT SUPPORT
  $ENV{HTTPS_CERT_FILE} = 'certs/notacacert.pem';
  $ENV{HTTPS_KEY_FILE}  = 'certs/notacakeynopass.pem';
(from http://search.cpan.org/~chamas/Crypt-SSLeay-0.51/SSLeay.pm) does 
(or point me @ a nice url or something)?

I went on a adventure today writing a little (perl) script to send xml 
requests over ssl to an apache server.
Basically i wanted to grant access/reject requests depending on the 
presents of a cert (from the client).
I assumed that's what a client cert did or is that CA CERT PEER 
VERIFICATION?
The script works, but I think i've implemented the wrong solution (d'oh 
:)

I've:
        - Been on a google (got even more confused).
        - Been reading the RFC's & Spec's (got very bored).
        - Been drinking to forget.
Apologies if this is a really simple/silly question: Cost of losing 
face - Nothing!

Thanks
    Robin...