An application that creates a DTD or XDR schema from an existing XML Schema can provide a useful tool for a business that deals exclusively with DTD or XDR schemas, but acquires and works with third party schemas that are in the XML Schema format. Such an application can read the XML Schema, and write a DOM document based on the properties returned. Manually reading the XML Schema would be less efficient than using the SOM to walk through its elements. You can also use the DOM to efficiently create the DTD or XDR document.