XML::SAX::Base has a very simple task - to be a base class for PerlSAX drivers
and filters. It's default behaviour is to pass the input directly to the output
unchanged. It can be useful to use this module as a base class so you don't have
to, for example, implement the characters() callback.

The main advantages that it provides are easy dispatching of events the right
way (ie it takes care for you of checking that the handler has implemented that
method, or has defined an AUTOLOAD), and the guarantee that filters will pass
along events that they aren't implementing to handlers downstream that might
nevertheless be interested in them.

WWW: http://search.cpan.org/dist/XML-SAX-Base/