H. G. Muller wrote on Sun, Apr 21, 2019 07:28 AM UTC:
The problem with multi-letter ID is that they do not work in FEN when mixed with single letter. (And even if not mixed, it leads to FENs that are unreadable for humans). As an alterative to FEN there could be DEMN, which uses piece IDs whith a first-letter upper case and the optional following letters in lower case, and then lists the white and black pieces in separate sections concatenated by #. (Advantage is that that this also works for multi-player variants.) I was still not happy with the human redability, though.
In XBoard I finally adopted the solution of ' dressed letters', where each piece ID is a single letter (captital / lower case used to distinguish color in FEN), optionally followed by a punctuation sign, like quotes or an exclamation point. So L, L' , L`, L" and L! all indicate different pieces. This gives FENs that are quite readable. It can also be use in SAN, but there alternatively only the letter could be used, conventional coordinate disambiguation sloving the problem that G can both be Gold an Great General. (The WinBoard Alien Addition currently uses this method in Tenjiku Shogi.)
Note that there is not really any need for pieces of opposing armies to have different ID; it should always be clear whose turn it is (in SAN), or which color (in FEN). So both Bishop and Bede can be B without causing any problems, as they will never occur in the same army.
The problem with multi-letter ID is that they do not work in FEN when mixed with single letter. (And even if not mixed, it leads to FENs that are unreadable for humans). As an alterative to FEN there could be DEMN, which uses piece IDs whith a first-letter upper case and the optional following letters in lower case, and then lists the white and black pieces in separate sections concatenated by #. (Advantage is that that this also works for multi-player variants.) I was still not happy with the human redability, though.
In XBoard I finally adopted the solution of ' dressed letters', where each piece ID is a single letter (captital / lower case used to distinguish color in FEN), optionally followed by a punctuation sign, like quotes or an exclamation point. So L, L' , L`, L" and L! all indicate different pieces. This gives FENs that are quite readable. It can also be use in SAN, but there alternatively only the letter could be used, conventional coordinate disambiguation sloving the problem that G can both be Gold an Great General. (The WinBoard Alien Addition currently uses this method in Tenjiku Shogi.)
Note that there is not really any need for pieces of opposing armies to have different ID; it should always be clear whose turn it is (in SAN), or which color (in FEN). So both Bishop and Bede can be B without causing any problems, as they will never occur in the same army.