Folkert van Heusden wrote:
When a chessengine or user enters a SAN move, do I need to know what
moves he is capable at that moment of doing? Or is it enough to know what
pieces are where on the board?

You should be able to get the exact move given just the pieces on the
board and a correctly formatted SAN move, that includes all proper
disambiguation such as Ngf3 or Rhd1.

Ah ok, really glad to hear that. Thanks!

Note that this implies that the SAN move that you are trying to make is
legal! You may need to do some checking just to make sure that a move
doesn't expose the King to check, or that castling or en passant are
truly legal.

So, to be more precise, I should have said "given a full FEN of the
position and a SAN move, you should be able to determine the exact
move".

jm