This module 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.