XML Example File AutoWorldDesc.xml
The first time this file is run, the DefaultAction would be set to add; afterwards, the PREFERENCES element could be removed (or its DefaultAction set to traverse), and any updates to elements would have their specific action attribute set to whatever is appropriate (that is, add or remove or (possibly) update). The action on the METAUSERREF elements should be set to traverse after the first run also.
Remember that the PREFERENCES tag can be used in many different places. See the DTD file for details.
Finally, note that the DTD file here is located on a WEB server (on the local host). Set the file path for this file to whatever is appropriate for your environment (the DTD file is installed in the %METAHOME%\bin folder).