The XMLQuery Working Group has published two Group Notes:
XQuery Update Facility 3.0. This document defines an update facility that extends the XML Query language, XQuery. The XQuery Update Facility 3.0 provides expressions that can be used to make persistent changes to instances of the XQuery and XPath Data Model 3.0.
XQuery Update Facility 3.0 Requirements and Use Cases: This document specifies goals, requirements and use cases for the XQuery Update Facility 3.0. XQuery 3.0: An XML Query Language provides queries but has no support for adding new values or changing existing values. The XML Query Working Group intends to add support for updates in a future version of XQuery. This document only contains requirements that have not been previously met by XQuery Update Facility 1.0.