Adding to the OPML export header


#1

Is there a way to, say, add information to the header when exporting from OO5 to OPML?

More specifically, the header for the OPML file looks like

 <?xml version="1.0" encoding="UTF-8"?>
 <opml version="2.0">

I would like to make it possible to include other files, so I’d like to have a header which looks like

 <?xml version="1.0" encoding="UTF-8"?>
 <opml version="2.0"
    xmlns:xi="http://www.w3.org/2001/XInclude">

I guess I could use a script to postprocess the file to add the extra text, but I was wondering if would be something I could tweak within OO5.