That might technically work, but I do not see any positive in hijacking the e.p. square in this way. The ep square is used by the code handling en passant - it won't and shouldn't know anything about imitators. Sure, I could program the en passant rule to just ignore values that don't seem appropriate, but that is just a hack and hacks don't lead to long term code understandably or maintainability. And, as you note, this wouldn't even work with the scenario where different colored Jokers move differently.
Some games just need additional state information to be stored - there's no way around it. For example, Carlos Cetina's Symmetric Chess needs to store the Bishop Conversion Rule properties. I don't think you will come up with a clever way to sneak that information into existing FEN structure. (This reminds me, I need to post on that page exactly how I've extended FEN to accommodate this. Been meaning to do that for a long time now.)
But I do agree that both Jokers having the same move is conceptually simpler and therefore preferable.
That might technically work, but I do not see any positive in hijacking the e.p. square in this way. The ep square is used by the code handling en passant - it won't and shouldn't know anything about imitators. Sure, I could program the en passant rule to just ignore values that don't seem appropriate, but that is just a hack and hacks don't lead to long term code understandably or maintainability. And, as you note, this wouldn't even work with the scenario where different colored Jokers move differently.
Some games just need additional state information to be stored - there's no way around it. For example, Carlos Cetina's Symmetric Chess needs to store the Bishop Conversion Rule properties. I don't think you will come up with a clever way to sneak that information into existing FEN structure. (This reminds me, I need to post on that page exactly how I've extended FEN to accommodate this. Been meaning to do that for a long time now.)
But I do agree that both Jokers having the same move is conceptually simpler and therefore preferable.