Internal is the internal subset, given as a string. If there was no internal subset, it will be undefined. Internal will contain all whitespace, comments, processing instructions, and declarations seen in the internal subset. However, comments and processing instructions will not appear if they've been processed by their respective handlers. This handler is called for xml declarations.
Version is a string containg the version.
Encoding is either undefined or contains an encoding string. Standalone will be either true, false, or undefined if the standalone attribute is yes, no, or not made respectively. If the name doesn't belong to any namespace, an undef is returned. Return a name, associated with a given namespace, good for using with the above 2 methods. The namespace argument should be the namespace URI, not a prefix.