Basically the same feature of including files is also available for use in the .xml, .pluginmap and .rkh files. At any place in these files you can place an <include> tag as shown below. The effect is that the entire contents of that XML file (to be precise: everything within the <document> tag of that file) is included verbatim at this point in the file. Note that you can only include another XML file.
<document>
[...]
<include file="another_xml_file.xml"/>
[...]
</document>
The attribute file is the filename relative to the directory the current file is located in.
