Attention: BeyondTV users

If you are using the -metaBTV option to generate BeyondTV .xml output files, I have a question for you:

To serve another purpose I would like to add some elements. I need to know whether extra elements will cause BTV to choke. Hopefully it will just ignore them. If you can provide a link to a format specification for these files, that might be helpful also.
OK, after 76 views and no responses, I'm sensing confirmation of my belief that Beyond TV support is a dead issue. I will be removing it.