Proposal to add standardized variation sequences for chess notation

[Christoph Päper]

Michael Everson <everson at evertype.com>:
> 
> Standardized variation sequences are the best way to achieve this simply and
> without needless duplication. :-)

I still agree with this assertion.

> > The distinction between white/black background might be of a different
> > nature. If you have arranged everything in a grid with the correct matrix,
> > then the color of the background is perhaps redundant, given that there is a
> > uniform convention for it.
> 
> Yes but you still want it to be reasonably legible when the OpenType ligatures
> fail.

This is were I don't follow.

> ▗▁▁▁▁▁▁▁▁▖
> ▕□︀▨︁□︀▨︁□︀▨︁♞︀▨︁▏
> ▕▨︁□︀▨︁□︀▨︁□︀▨︁□︀▏
> ▕□︀▨︁♔︀▨︁□︀▨︁□︀▨︁▏
> ▕▨︁□︀▨︁□︀▨︁♘︀▨︁□︀▏
> ▕□︀▨︁□︀▨︁♚︀▨︁□︀▨︁▏
> ▕▨︁□︀▨︁□︀▨︁□︀▨︁□︀▏
> ▕□︀▨︁□︀♙︁♛︀▨︁□︀▨︁▏
> ▕▨︁□︀♕︁□︀▨︁♖︀▨︁□︀▏
> ▝▔▔▔▔▔▔▔▔▘
> is far better than this:
> ▗▁▁▁▁▁▁▁▁▖
> ▕□︀□︀□︀□︀□︀□︀♞︀□︀▏
> ▕□︀□︀□︀□︀□︀□︀□︀□︀▏
> ▕□︀□︀♔︀□︀□︀□︀□︀□︀▏
> ▕□︀□︀□︀□︀□︀♘︀□︀□︀▏
> ▕□︀□︀□︀□︀♚︀□︀□︀□︀▏
> ▕□︀□︀□︀□︀□︀□︀□︀□︀▏
> ▕□︀□︀□︀♙︁♛︀□︀□︀□︀▏<< Is it the pawn or the queen that’s on the black square?
> ▕□︀□︀♕︁□︀□︀♖︀□︀□︀▏
> ▝▔▔▔▔▔▔▔▔▘

It *looks* far better in a multi-line plain text environment, but that's a
glyphic/typographic/stylistic argument. The semantics conveyed are redundantly
encoded this way, so I wouldn't say it was far better. This alternating pattern
is far more redundant than, say, pairs of opening and closing characters
(brackets, quotation marks).

Aside, good fallback isn't something the UTC seems to be concerned with lately,
see emoji subregion flags that are all represented by Waving Black Flag in
legacy implementations (possibly followed by TOFU).

> See? To parse this one you have to remember which of the white squares are the
> alternating black ones.

No, you only have to remember that A1, i.e. the lower left square initially
occupied by a white rook, is black. For legal moves, the color pattern hardly
matters, unless - regarding pawns - it was common practice to render the board
turned, i.e. with the white player not at the bottom, but at the top (or left or
right) side, and without alphabetic column and numeric row labels. 

> The colour of the matrix is NOT redundant for a human reader.

That's what this proposal is all about. It's a good and sound proposal, except
for the empty square.