Set SAX handlers on the resource handle given by
xh. SAX handlers should be a two dimensional array
with the format (all top level elements are optional):
array( [document] => array( start document handler, end document handler ), [element] => array( start element handler, end element handler ), [namespace] => array( start namespace handler, end namespace handler ), [comment] => comment handler, [pi] => processing instruction handler, [character] => character data handler )