Re: [css3-writing-modes] inconsistent handling of 'Tr' codepoints in 'text-orientation'

Koji Ishii wrote:

> This optional behavior is what UTR#50 defines:
>> Tr Same as Tu except that, as a fallback, the character can be
>> displayed with the code chart glyph rotated 90 degrees clockwise.
> 
> So if you think this behavior is unnecessary, you need to feedback to UTC.
> The members at UTC raised a concern because CSS does not allow the
> behavior as defined in UTR#50. The need for allowing this optional
> behavior is to allow an implementation that follows UTR#50.

If your intent was to specify CSS behavior via UTR50 I don't think
that's really appropriate.  I agree with the statement, the character
"can be displayed".  But Unicode is a character standard, not a font
and text engine standard.  You need to separate the two.

Given actual fonts and real world conditions for the web platform, I
don't see an actual need to require or optionally allow such fallback,
since OpenType functionality and actual fonts already provide the
necessary alternates.  In some closed-end non-OpenType environment,
the Tu/Tr distinction might be useful, but since fonts already support
both Tu and Tr codepoints, the fallback behavior is unnecessary for CSS.

Just in case this wasn't clear, I see no issue with Unicode here, I
only see an issue with what you've specified for CSS.

Could you explain more clearly under what conditions this fallback is
needed?  What content rendered with what set of fonts makes this sort
of fallback desirable?

Regards,

John Daggett

Received on Wednesday, 25 September 2013 05:25:43 UTC