Proposal to add standardized variation sequences for chess notation

[Kent Karlsson]

Den 2017-04-06 03:05, skrev "Michael Everson" <everson at evertype.com>:

> On 6 Apr 2017, at 01:54, Kent Karlsson <kent.karlsson14 at telia.com> wrote:
> 
>>>> - some bidi fix [preferably making the box/border drawing characters bidi
>>>> "L", if possible; otherwise a caveat that if there is an expectation to
>>>> paste in such a board into an RTL document, bidi controls need be used to
>>>> LTR the board]).
>>> 
>>> I donąt know if there is a problem here and am not able to offer a solution
>>> if there is. I donąt object to a solution, if there is a problem.
>> 
>> I would think
> 
> Come on. This is a serious proposal.

I agree! ;-)

> I'm glad you support it, but if you are
> going to raise an issue like this, "I would think and guess about a problem"
> isn't the same as "I have tried and here's an actual problem".

I apologise for my slightly cautious way of expressing myself...

All the characters in the "chess board lines" (apart from spaces, if any),
are of bidi category ON or NSM. So there is no character that "sets" a bidi
direction of the lines ("paragraphs"). So if the bidi setting for display is
set to default to RTL, each of the chess board lines will be reversed in
display. Now, since the border characters are not mirrored, the left and
right side of the board side lines will be somewhat botched. Which is very
visible in that it is ugly. (And I guess(!) the reader will notice that...)

I'm not a bidi expert, but I know that much about bidi (and so should
you...).

> Roozbeh, there's an issue that might benefit from your expertise. Can you look
> into it? Discussion needn't occur here, but offline with Kent and me, if you
> prefer. 
> 
>> that anyone pasting a chess board (ŕ la your proposal) to an RTL context will
>> see that something went amiss,
> 
> Will they? Why?

Since the border characters are not mirrored (they do not have the
mirroring property), the left and right side of the chess board side
lines will be somewhat botched. Which is visible/ugly. Indeed, the entire
chess board will be mirrored (though none of the individual glyphs), but,
though visible, that whole-mirroring (line reversal) is easier to miss.

>> and also know enough about bidi to set the bidi context to LTR for the chess
>> board(s),
> 
> RTL users understand the problems of cutting and pasting LTR text and symbols,
> certainly. LTR users don't.
> 
>> either by some setting, or by inserting bidi control characters.
> 
> Well, if there's a problem it should be well-defined so it can be tackled.
> 
>> So a small caveat is all that is necessary. Like: "The chess boards are
>> assumed to be set in a left-to-right bidi context."
> 
> THAT I can put into the document, but since chess is as important in both the
> RTL and LTR worlds, it would be good to know what's what.

See above.

/Kent K

> Thank you again for your thoughtfulness,
> 
> Michael