A Data Model for Strongly Typed XML

From Dare's article:
http://www.xml.com/pub/a/2002/12/19/datamodel.html

"The XQuery and XPath 2.0 data model presents itself as a viable data model
for processing XML in strongly typed usage scenarios. The loose coupling to
the W3C XML Schema type system is especially beneficial because it both
provides an interoperable set of types, yet does not limit one to solely
those types."

Did I miss something? How is the XQ and XP data model loosely coupled to XML
Schema types?