Descriptions of the Help&Manual XML format ?

I'm looking for a description of the Help&Manual XML format to fix an old bug (UX bug?) in OmegaT:

https://sourceforge.net/p/omegat/bugs/523/

https://sourceforge.net/p/omegat/code/ci/master/tree/src/org/omegat/filters3/xml/helpandmanual/

I've checked the H&M site and besides for a (very) few screenshots there is almost no information regarding what the format looks like (my hunch is that it's a DITA-like format, based on the presence of map, topic etc.).

I'd love pointers if any of you have some.

-- 
Jean-Christophe Helary @
https://traductaire-libre.org
https://mac4translators.blogspot.com
https://sr.ht/~brandelune/omegat-as-a-book/