We have the technology for at least 6 concurrent alliances (A-F) (BA/Eureka thread)

[linay]

Well, the game calls them "Alliance A", "Alliance B", etc..instead of "Party A", "Party B", so, as weird as it seems, it's correct.

I think it's just to make it easier for you to know you're in an alliance. I like to think of them as being short for Alliance Party A, etc.