DB2 10.5 for Linux, UNIX, and Windows
XQuery and XPath data model
XQuery expressions
operate on instances of the XQuery and XPath data model (XDM) and
return instances of the data model.
The
XDM provides an abstract representation of one or more XML documents
or fragments. The data model defines all permissible values of expressions
in XQuery, including values that are used during intermediate calculations.
Parsing of XML data into the XDM and validating the data against a schema occur before data is processed by XQuery. During data model generation, the input XML document is parsed and converted into an instance of the XDM. The document can be parsed with or without validation.
The XDM is described in terms of sequences of atomic values and nodes.