We get a lot of complaints on bugs.php.net and the mailinglists, that getElementById() doesn't work in the DOM implementation. This is of course wrong, the implementation just works fine ;) But contrary to popular believe, getElementById() does not return the element with the matching attribute named āidā by default. Therefore I wrote a little article about the whole problem and an easy solution with the recent introduction of the xml:id support in libxml2. As it's a wiki page, feel free to add your additions and corrections.