XDM is the foundation of
XPath 2.0 and defines the
Data Model for
XPath 2.0 (and consequently
XQuery and
XSLT 2.0, which are both based on
XPath 2.0). XDM is built on top of the
XML Infoset (the abstraction of an
XML document),
PSVI (type annotations in the
XML Infoset as the result of
XSD validation), the simple datatypes of
XSD, and additional concepts. The most important additional concept is that of a "sequence", which embraces both simple datatypes and the
XML-derived nodes.