Removal of XDR Schema Support in MSXML 6.0


Support for XML-Data Reduced schemas (XDR) has been removed from MSXML 6.0.

XDR is a proprietary schema language that was implemented as part of MSXML prior to the introduction and acceptance of XSD. Its primary purpose is the same as XSD: to provide validation for XML documents. The core concepts around validation and content models are the same for the two types of schemas. However, the industry has come to a consensus on using XSD schemas; XSD is a standard published by the World Wide Web Consortium (W3C).

Impact on Programming Interfaces

The removal of XDR support impacts some of the schema programming interfaces. For example, in MSXML 4.0 and MSXML 5.0 you could add either an XDR or XSD schema to the schema cache. In MSXML 6.0, you can only add XSD schemas to the schema cache.

XDR Data Type Support

XDR schemas provided extensive data type support. This 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>  

For more information, see XDR Schema Data Types Reference.

MSXML data type support is provided for legacy applications. It is recommended that new applications use XSD schemas and XSD data types.