For most situations there's only one way to move the reader: forward,
xmlReaderRead(), which moves to the next item type.
The exception is attributes. The reader does not stop on attributes
when advancing with
xmlReaderRead(). instead, all attributes of
an element are read when the element is read. They can then be
randomly accessed and iterated over as long as the reader remains on
the element (which is until
xmlReaderRead() is again called).