RE: Should mathbackground have (and default to) a transparent value?

Hi.

The question of how it should work when mixing with non-MathML is not defined.  Technically, MathML 2 doesn't allow any non-MathML markup to be mixed in.  This has been an extremely contentious issue, and we have been talking to the compound document format working group for a long time about defining something like an XHTML+MathML+SVG profile that works all that out.  Part of the problem is that it is basically unimplementable in most situations, with the notable exception of the yours, where you've implemented them all together.  So, you are on your own there, for now anyway.

Within MathML itself, inheritance is straightforward, I believe.  To determine the value if one is not explicitly set on an element, one looks up the chain of parent elements until one finds a value.  If one reaches the <math> node without finding an explicit value, then one uses the value from the "ambient rendering environment".  In non-(X)HTML settings, that means the caller of the MathML renderer has to provide a value as the default, along with all the other defaults for values that are inherited, like the font size, display style and so on.

Of course, in (X)HTML, chances are that value is "transparent" as you point out.  That suggests to me that there really ought to be a 'transparent' value for mathbackground too. That is just my personal opinion, though.

I guess I should consult with the rest of the working group and see if there is some reason for omitting it that I am forgetting.  Otherwise, I would be in favor of adding it as a valid value in MathML 3.

--Robert


-----Original Message-----
From: www-math-request@w3.org on behalf of L. David Baron
Sent: Thu 11/29/2007 5:43 PM
To: www-math@w3.org
Subject: Should mathbackground have (and default to) a transparent value?
 

The mathbackground attribute is defined in
http://www.w3.org/TR/2003/REC-MathML2-20031021/chapter3.html#presm.commatt
to default to 'inherited'.  Yet it is allegedly similar to the CSS
background-color property, which is not inherited.  If it is
inherited, how does it work (particularly when mixing with
non-MathML)?  If not, should it have a transparent value like the
background attribute on mstyle:
http://www.w3.org/TR/2003/REC-MathML2-20031021/chapter3.html#id.3.3.4.2
and default to that value?

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/