In addition to the string and other primitive types defined by the World Wide Web Consortium (W3C) XML 1.0 Recommendation, Microsoft® XML Core Services (MSXML) supports a rich set of data types. It also supports conversions between the primitive types and these rich data types.

Data types are referenced from the data type namespace "urn:schemas-microsoft-com:datatypes". To use data types within an XML schema, declare the data type namespace within the schema document. This documentation assumes that the data type namespace has been assigned the dt prefix, as shown in the following example.

<Schema name="myschema"
        xmlns="urn:schemas-microsoft-com:xml-data"
        xmlns:dt="urn:schemas-microsoft-com:datatypes">
  <!-- ... -->
</Schema>

XDR schema support has been removed from MSXML 6.0 and later.

XDR data type support continues to be available in MSXML 6.0, even though XDR schema support has been removed. In MSXML 6.0, you can declare an element to be of a certain type as follows:

<root xmlns:dt="urn:schemas-microsoft-com:datatypes">

<count dt:dt="int" >5</count>

<price dt:dt="number" >44.95</count>

</root>