Comment 2 for bug 894989

I concur with guest's suggestion. However, rather than a separate list of groups as has been suggested elsewhere, I would suggest something like this:

[ADOG]
SelectionGroup=YADOG
BuildLimitGroup=DOG,YADOG,YDOG

[DOG]
SelectionGroup=YDOG
BuildLimitGroup=ADOG,YADOG,YDOG

...and so on.
The idea is that the game would only have to lookup IDs from the unit that we are interacting with, rather than going off to hunt some other data.