Proposal to add standardized variation sequences for chess notation

[Kent Karlsson]

Den 2017-04-03 14:50, skrev "Michael Everson" <everson at evertype.com>:

> On 2 Apr 2017, at 18:52, Richard Wordingham <richard.wordingham at ntlworld.com>
> wrote:
>> 
>> You forgot the most important setting though - that the higher-order
>> protocols allow symbols to be displayed left-to-right. If the direction
>> should happen to be right-to-left, not only is the game mirrored, but the
>> board edges don't work properly, as the glyphs are not mirrored.  One needs
>> each bidi-paragraph to be forced to the correct order, e.g. by use of LRM
>> before and after, or, if the board is recorded right-to-left, RLM or ALM
>> before and after.
> 
> None of the characters listed in §3 has a mirroring property.

Right, but most of them have bidi property ON (other neutral), so in
a right-to-left context, the chess board characters will be reversed
(on each line, but the VSs (which are NSM) still go with their base).
This would
1) mirror the chess *board* display (but not the chess *piece* glyphs)
2) mess up the corner glyphs, which are not mirrored; and also
   the RIGHT/LEFT ONE EIGHTH BLOCK glyphs, which aren't mirrored
   either.

Issue 2 will result in ugly display.
Issue 1 will confuse the reader, mirroring the entire chess board (if
one disregards the ugly display of the corner and left/right borders).

Hence the chess board lines should be displayed in a strong left-to-right
context (either via bidi markup characters, or via some higher order
bidi markup mechanism, such as the "bidi" attribute in HTML). Though in
most cases (not Arabic/Hebrew/... document), the bidi context will default
to left-to right...

For cut-and-paste to work well also when pasting to a right-to-left
context document, bidi markup characters are probably better than using
a higher-level attribute. I think that is why Richard argues for using
bidi characters to make the lines strong left-to-right (without having
to surround each chess board line with visible strong l-t-r characters).

You might argue for making the board corner and board left/right border
characters strong l-t-r. Not sure if that would sit well with the UTC...

/Kent K