==XQUF Concepts==
There are a few specialties around XQuery Update that you should know about. In addition to the <b>simple expression</b>, the XQUF adds the <b>updating expression</b> as a new type of expression. An updating expression returns only a PUL as a result which is subsequently applied to addressed databasesand DOM nodes. A simple expression cannot perform any permanent changes and returns an empty or non-empty sequence.
===Pending Update List===