W3C home > Mailing lists > Public > www-math@w3.org > January 2010

Re: Directionality attribute

From: Frédéric WANG <fred.wang@free.fr>
Date: Tue, 05 Jan 2010 14:26:20 +0100
Message-ID: <4B433DFC.9080706@free.fr>
To: David Carlisle <davidc@nag.co.uk>
CC: www-math@w3.org
 > I would suggest that we add "and math" after  "no other elements 
except mstyle"

The sentence I quoted says nothing about <mrow/>, that accepts dir but 
not mathvariant/mathsize. I would rather suggest to remove "and on no 
other elements except mstyle" since anyway the attributes allowed in 
math/mstyle/mrow are indicated elsewhere.

 > Either we should say dir is allowed but deprecated (which has a kind 
of logic, but may be strange to deprecate a new attribute) or the schema 
should not include TokenAtt but instead include each of the tokem 
attributes except for dir individually. Something for the WG to decide.
 > it could potentially affect the rendering of glyphs from fonts that 
are subject to mirroring in a bidirectional context.

Removing the dir on glyph sounds better IMO. It is not clear when 
mirroring needs to be applied for glyphs coming from fonts (I guess the 
bidi algo only specifies mirroring for unicode characters?) or images. 
Also section says that mglyph is neutral, so this would suggest 
it has no directionality.

 > the fact that it's empty doesn't necessarily mean that it doesn't 
have an effect, in this case it could (perhaps, I think) affect choices
 > Currently dir is added automatically by the schema generator 
following automatically from the fact that mspace is classified as a 
token attribute. I think (personally) it is simpler to allow the 
attribute even if there is no obvious use for it rather than say 
everywhere that we discuss attributes on token elements "except mspace".

I haven't really thought about linebreaking with mspace but I would have 
think it is affected by the directionality of the parent not of the 
mspace token itself. However keeping consistency in all token elements 
sounds good, even if dir may not be use for mspace.
Received on Tuesday, 5 January 2010 13:24:19 UTC

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