XML Includes

One XML data file can include other XML data files. A fuller write-up of this feature can be found at PaneTalk XML Includes.
In excessive brevity:

1. Use the -filter IncludeProcessor on the Merge command line.
2. Define the xi namespace on the main XML file's root tag:
   <XmlData xmlns:xi="http://www.w3.org/2001/XInclude">
3. Reference the XML file to be included like thus:
   <xi:include href="a file name.xml"/>