Very nice, added it to the
wiki (which should state what revision this is available in, rather than just "latest SVN".
I'd really like to see this expanded. I'd like to see the ability to create a link to a faction in the same techtree (impossible because you can't have two factions of the same name in the same techtree), and to make that useful, the ability to edit the rest of the faction XML and overwrite the link. So for example, Annex (I think) has a few different versions of the same faction, with the only difference being the starting units (one might have an extra worker and be geared towards expansion while one might have an extra warrior and be geared towards combat, etc). Doing such a thing requires copying the entire faction and tweaking every link to the original resources. This new link element could make a simple starting unit change considerably easier, if expanded.
