Pike autodocs scripts, a helping hand, please?

Just one, little question :) - is there any documentation about the meaning of the tags/attributes in refdoc/structure/modref.xml? I'm trying to make autodocs work on Caudium tree and I'm having problems with one subtree where the documentation extracted from this sample tree:

Cache.pmod/Client.pike Storage.pmod/Client.pike

Is merged in a flat fashion (the sub_module.xml files from those dirs are merged as if they were in one directory) which generates a 'Duplicate class' error. I imagine it has something to do with the structure defined in modref.xml (or, rather, it's Caudium equivalent) - I'd really, really appreciaty any hints and help on that one. :)

TIA