SimpleXML and documentation

Hi I'm working on a PHP5 project with some simple XML. I've seen examples of SimpleXML in CVS ("tests" and "examples" directories) but cannot find any real documentation. Is there any docs somewhere ? where ? If not, does someone can answer a few questions ? - how do I add an element ? - can I change the text content of an element ? if yes, how can I deal with something like "<element> text1 <sub/> text2 </element>" ? - can I delete elements ? attributes ? - how do I deal with namespaces ? I've seen a "register_ns" method but do not know if registration is inherited, and do not know how to use namespaces after registration ($element->ns:subelement is not a valid PHP syntax) - I've seen many times that simpleXML is limited to 3 levels of nesting but there is a phpt with 4 levels. Is there a limitation ? if yes, which one ? thanks per advance for all answers. -- Eric Daspet