If Fixed is true, then this is a fixed attribute. Name is the document type name. Internal will be true or false, indicating whether or not the doctype declaration contains an internal subset. This handler is called for XML declarations. Version is a string containg the version.
Encoding is either undefined or contains an encoding string.
Standalone is either undefined, or true or false. Undefined indicates that no standalone parameter was given in the XML declaration. 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.