There are two more things that should be considered.
Both of them unlikely to influence a position, but they can matter - just like the en passant target.
The fifty move rule[0] is quite simple, just store a number, fits in five bits. But the threefold repetition rule[1] is quite a pickle - it basically means that to know everything about a position you need to know every position that occurred before it.
The fifty move rule[0] is quite simple, just store a number, fits in five bits. But the threefold repetition rule[1] is quite a pickle - it basically means that to know everything about a position you need to know every position that occurred before it.
[0] https://en.wikipedia.org/wiki/Fifty-move_rule [1] https://en.wikipedia.org/wiki/Threefold_repetition