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Re: [MathML3-last-call] comments from HTML WG

From: Philip Taylor <pjt47@cam.ac.uk>
Date: Thu, 19 Nov 2009 20:09:42 +0000
Message-ID: <4B05A606.2050306@cam.ac.uk>
To: David Carlisle <davidc@nag.co.uk>
CC: www-math@w3.org, public-html@w3.org
(Not speaking on behalf of anyone or suggesting any spec changes, just 
commenting on a few things I saw here...)

David Carlisle wrote:
>> 8. In the section describing color[3] you reference color names from
>> HTML4. Is there a reason MathML doesn't use css3-color SVG color
>> keywords instead of HTML4 color keywords?
> Initially (MathML1) there was no css3-color or svg.
> We did look briefly at extending this list but it wasn't clear that this
> would be useful: it doesn't really add any new functionality (since hex
> colours are supported)

Using CSS3 Color could add RGBA functionality, which would be new. (Not 
saying it's necessarily a good idea, though!)

> and typically isn't currently supported by MathML2 systems.

SVG colors seem to be supported by Firefox 3.5: 
(I can't say anything about other MathML systems, though.)

> HTML5 has these extended color names but introduces
> them as 
>       "Some obsolete legacy attributes parse colors in a more
>        complicated manner,"
> which doesn't really encourage these colours to be added as a new feature
> to other specs such as MathML3

The obsoleteness is about the attributes and the parsing algorithm, 
rather than about the colours - that part of the spec is needed for 
cases like <body bgcolor="cheese"> (a nice greenish yellow colour, since 
it's parsed like #c0ee0e (for legacy reasons), and it's non-conforming 
anyway because bgcolor is never allowed).

As far as I can see, the only place HTML5 uses colours in a non-obsolete 
fashion is for <canvas>, and there it refers to CSS3 Color for the full 
list of colour types and keywords. All other uses of colour in a web 
browser are just CSS, so HTML5 is not involved in the definition of 
that; browsers largely follow CSS3 Color there.

Philip Taylor
Received on Thursday, 19 November 2009 20:10:16 UTC

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