I wanted to add a unit to the skaven that onebattlesummoned a load of giant rats at the start of combat. That's cool, I know how to do all that. So I get it done and notice something odd - the rats start the battle facing the wrong way - left when my guys are going to the right. It looks weird so I resolve to fix it.
A LOT of tinkering later, still no luck. I remember Burn's Breton mod has the exact same mechanic, so I fire it up and check. His units are fine - they face the right way.
I spend an hour or two codeswapping between the two mods and ruling things out. I joke on irc that it's probably going to be the nation number or something crazy like that. And that if it is, it will be based on whether it's odds or evens.
Believe it or not, after a bunch more testing, I find I'm right. Whenever Breton is set to an odd nation number, the summons appear facing the wrong way. Whenever even, the right way. Same for the skaven.
So now the mods with onebattlespell summons will need to take the even nation numbers. Crazy.
Just thought I'd share.