XMLReader: missing rewind()

I'm missing a function like $reader->rewind() to set the internal cursor of
the reader to its starting position.

further i didn't found such rewind() at
http://xmlsoft.org/html/libxml-xmlreader.html , the home of libxml's
xmlreader...

i think the only way getting out is to $reader->close() and
$reader->XML(...) again??

Can somebody help me with that?

thanks in advance
vivian