The node element with @id=1 is copied and subsequently assigned a new QName using the rename expression. Note that the transform expression is the only expression which returns an actual XDM instance as a result. You can therefor use it to modify results and especially DOM nodes. This is an issue beginners are often confronted with. More on this topic can be found in the [[Update#Returning Results|XQUF Concepts]] section.
The following example hopefully clears things up a bit:. The <entry> element which is copied can also be replaced by a database node. In this case, the original database node remains untouched as all updates are performed on a copy.
<pre class="brush:xquery">