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RE: SVGMobile12] SVGT12-183: Rules for handling "unsupported" values don't work when properties are syntactically correct and specified using W3C mechanisms other than SVG attributes

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 11 May 2006 10:37:27 +0000 (UTC)
To: Scott Hayman <shayman@rim.com>
Cc: www-svg@w3.org
Message-ID: <Pine.LNX.4.62.0605111031591.21459@dhalsim.dreamhost.com>

On Thu, 11 May 2006, Scott Hayman wrote:
> 
> Looking at the part of the CSS 2.1 spec that talks about url() property 
> values [1], it seems as if it is left up to the UA as to how to handle 
> invalid URIs or URIs that designate unavailable or inapplicable 
> resources.

It varies per-property, but in general yes.


> The SVG working group would like to specify this behaviour, so it 
> doesn't look like we will be able to just refer to the CSS spec in this 
> matter.

Agreed; hence my proposal in the original raising of this issue. :-)


> Given what we are trying to do, would it be correct to say that the 
> computed value of the property is as if it had been inherited?  I know 
> that this may not be 100% correct spec terminology, but I'm just trying 
> to get agreement on the concept using CSS terminology.

No, because inheritance happens before the stage at which you find out 
that the URI is invalid.

The only real option I can see is to give a value, e.g. 'none', and 
require that if the URI is not valid, then that value must be used 
instead. It's too late, by time the time you have this property, to base 
it on other values of that property that the author may have specified 
(e.g. on the parent element or in stylesheets).

Well, I guess you could say that if the URI is invalid then the UA must 
use the computed value of the element's parent element. It would have the 
same effect as inheritance though it wouldn't actually be inheritance from 
a technical perspective.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 11 May 2006 10:37:38 GMT

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