Single Comment

Yes, I understand what you meant by FEN for movement, but it sounds
rediculous. Especially since there are already plenty of standards for
move notation (with limited scope, e.g. Chess), that do have sensibla
names. Like SAN = Standard Algebraic Notation.

I understand that you don't mind that the mve notation would make use of
knowledge of the rules of the variant. This does imply that the same move
could have different notation in different variants (because in one
variant the move would need extra info to disambiguate it, while in others
it would not (e.g. promotion to Q in Shatranj, if Ferz is represented by Q,
would be implied, while in Chess there woud be a choice.)

I am not sure if you could call something a universal standard if it would
need knowledge of the rules of the variant to define the meaning. If it was
allowed to draw on the rules of the variant, such a system is likely to
degenerate to the union of the most-convenient notations for each variant.
In Chess an Alfil jumps without capturing the piece it jumps over, in
checkers a jump implies a capture. I guess the most important part of the
standard would not be how you can describe mutations to th board, but in
stead when you have to do it, and when you have to omit it. If you would
indicate a drop with '@', as in SAN (e.g. N@e4), in Go the fact the
piece type as well as the fact that it is a drop would be implied, and
there would no reason to include tem in the notation. So Go moves simply
become the indicator for the cell where you drop, everything else could be
implied.

If it is allowedto use knowledge about the game when interpreting the
moves, the need for many delimters disappears. Why separate the FromSquare
and ToSquare by a hyphen? You could simply concatenate the square
coordinates if it their syntax is known. a character behind that could
indicate the new state of the target cell, if different from the state of
the source cell 9as with promotions). Only non-implied side-effects would
hav to be described. e1g1 would still be a perfect notaton for castling,
as the Rook move is fully implied by it.