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RE: Specification problem - referential style chaining.

From: Sean Hayes <Sean.Hayes@microsoft.com>
Date: Sun, 7 Dec 2008 12:42:38 +0000
To: "Glenn A. Adams" <gadams@xfsi.com>, Public TTWG List <public-tt@w3.org>
Message-ID: <90EEC9D914694641A8358AA190DACB3D2FCE9A217C@EA-EXMSG-C334.europe.corp.microsoft.com>

Well as you once said, understanding a spec is the art of reading carefully <grin/>. However notwithstanding that, I believe we should try and make things as clear as possible. My argument is not with the algorithm, which I think we both agree on, but the manner in which it is expressed.

I note also in 8.4.1 it defines inline as "direct specification of an attribute from the TT Style Namespace or TT Style Extension Namespace on the affected element".
Which, since the intro to 8.4 is defining association to content matter, I would take to mean that style attributes on style elements are not 'inline', and this rule is not applicable in the manner you state.

Also, where does LEFT-PRECEDENCE come from? I don't see how that is related to:
" If the same style property is specified in more than one referenced specification, then the last referenced style specification applies, where the order of application starts from the affected element and proceeds to referenced style specifications, and, in turn, to subsequent referenced style specifications.";

My reading of this phrase would be a RIGHT-PRECEDENCE operator, wherein lies my issue. I believe that defining referential style application in terms of a tree walk is a clearer exposition.

Sean Hayes
Media Accessibility Strategist
Accessibility Business Unit
Microsoft

Office:  +44 118 909 5867,
Mobile: +44 7875 091385


-----Original Message-----
From: Glenn A. Adams [mailto:gadams@xfsi.com]
Sent: 07 December 2008 00:52
To: Sean Hayes; Public TTWG List
Subject: Re: Specification problem - referential style chaining.

Ah, I misunderstood you. In any case, let's decode your example a bit more
carefully:

>>             <style id="s1" tts:color="brown" />
>>             <style id="s2" style="s1" tts:color="black"/>
>>             <style id="s3" style="s2" />

s1 is easy, and it means:

s1 -> { <tts:color,brown> }

s2 on the other hand, is derived as follows:

s2 -> LEFT-PRECENDENCE < { <tts:color,black> }, s1 >
   -> LEFT-PRECENDENCE < { <tts:color,black> }, { <tts:color,brown> } >
   -> { tts:color,black }

[N.B. Section 8.4.1 says "Style properties associated by inline styling are
afforded a higher priority than all other forms of style association.", so
that in resolving s2, the inline style tts:color has precedence over
referential styling style="s1".]

s3 -> s2
   -> { tts:color,black }

We get black, and not brown. So perhaps there is no problem here.

G.

On 12/7/08 7:19 AM, "Sean Hayes" <Sean.Hayes@microsoft.com> wrote:

> I wasn't talking about lexical order of elements, but of chains with multiple
> links. In a single chain the last referenced style would be the most distant
> from the affected element; which is wrong.
>
> Sean Hayes
> Media Accessibility Strategist
> Accessibility Business Unit
> Microsoft
>
> Office:  +44 118 909 5867,
> Mobile: +44 7875 091385
>
>
> -----Original Message-----
> From: Glenn A. Adams [mailto:gadams@xfsi.com]
> Sent: 06 December 2008 22:49
> To: Sean Hayes; Public TTWG List
> Subject: Re: Specification problem - referential style chaining.
>
> I disagree. The lexical order of the style element in the document should
> have no affect on the order of style resolution in the case of multiple
> style chains. The reason for this is that these style specification chains
> are semantically ordered via id references, and not lexically ordered
> (according to appearance in document order).
>
> It would also be more difficult for a processor to resolve styles using a
> combination of style id references and the order of appearance of the
> defining element.
>
> The spec should not be changed.
>
> Glenn
>
>
> On 12/6/08 10:01 PM, "Sean Hayes" <Sean.Hayes@microsoft.com> wrote:
>
>>
>> The spec currently says:
>>
>> " If the same style property is specified in more than one referenced
>> specification, then the last referenced style specification applies, where
>> the
>> order of application starts from the affected element and proceeds to
>> referenced style specifications, and, in turn, to subsequent referenced style
>> specifications."
>>
>> I don't think this is clear enough on how referential styling is supposed to
>> work.I think it works for cases such as the following:
>>
>>             <style id="s1" tts:color="brown" />
>>             <style id="s2" tts:color="black"/>
>>             <style id="s3" style="s1 s2" />
>>
>> An element referencing s3, would have color black.
>>
>> But in this case:
>>             <style id="s1" tts:color="brown" />
>>             <style id="s2" style="s1" tts:color="black"/>
>>             <style id="s3" style="s2" />
>>
>> The 'last' referenced style here is s1, and thus an element referencing s3,
>> would have color brown.
>>
>> This is not my understanding of how it is supposed to work, which is that the
>> order is a linearization of the tree in a depth first pre-order. Such that
>> the
>> 'last' element is black in both cases.
>>
>> To clarify this I suggest we edit the last sentence to:
>>
>> where the order of application is a depth first pre-order tree walk starting
>> from the affected element including referenced style specifications, and all
>> subsequent referenced style specifications."
>>
>> Example:
>>
>>             <style id="s1" tts:color="brown" />
>>             <style id="s2" style="s1" tts:color="black"/>
>>             <style id="s3" tts:color="green" />
>>             <style id="s4" style="s3" tts:color="yellow"/>
>>             <style id="s5" style="s4 s2" tts:color="pink" />
>>
>>             <p style="s5" tts:color="red">...</p>
>>
>> The depth first pre order for color here would be:
>>    green, yellow, brown, black, pink, red.
>>
>> The last and therefore applied color being red.
>>
>>
>> Sean Hayes
>> Media Accessibility Strategist
>> Accessibility Business Unit
>> Microsoft
>>
>> Office:  +44 118 909 5867,
>> Mobile: +44 7875 091385
>>
>>
>
>
Received on Sunday, 7 December 2008 12:44:19 GMT

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