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Re: XLink 1.1: behaviour of simple links without a show attribute

From: Jonathan Watt <jwatt@jwatt.org>
Date: Mon, 20 Mar 2006 23:35:56 +0000
Message-ID: <441F3C5C.2040401@jwatt.org>
To: Jonathan Watt <jwatt@jwatt.org>
CC: www-xml-linking-comments@w3.org, www-svg@w3.org, public-cdf@w3.org

Dear XML WG,

I haven't received a response from the WG to the issue I raised below, but I see 
you're going to CR. Could I know the status of this issue please?

Regards,
Jonathan

Jonathan Watt wrote:
> 
> XLink WG,
> 
> The current XLink 1.1 WD doesn't indicate clearly how conforming XLink 
> 1.1 applications should treat a simple link when the 'show' or 'actuate' 
> attributes are omitted (at least not in section 5.6 alongside the 
> description of the attributes where clarification would be most useful). 
> For example, what behavior should result from:
> 
>   <foo xlink:href="picture.gif">bar</foo>
> 
> Should it be treated as if it had xlink:show="replace"? Or as if it had 
> xlink:show="embed"? Or perhaps it's intended to be unspecified and left 
> up to the XLink application to decide how to behave?
> 
> I think the expected behavior should be made clear, even if just to say 
> explicitly that it is unspecified by the XLink specification, and XLink 
> applications may behave differently. However, what I'd actually prefer, 
> and what I think it would be most helpful, is if some text along the 
> following lines were to be added to section 5.6.
> 
>   If the show or actuate attributes are not specified, the
>   behavior of conforming XLink applications can be determined
>   by the specification, if any, governing the namespace of
>   the element. In other words, when omitted, conforming XLink
>   applications should behave as if the value "other" were
>   specified for these attributes. If the behavior is not
>   specified by any other specification or by some other
>   governing rules, then the behavior is unspecified. In this
>   case XLink applications may differ in their behavior.
> 
> I think text along these lines would be helpful for two reasons. Firstly 
> it will allow some of the conflicts between the SVG specifications (and 
> existing SVG content) and XLink to be resolved. For the following 
> elements in the SVG namespace:
> 
>   <a xlink:href="foo">bar</a>
> 
> the desired behavior is as if xlink:show="replace" and 
> xlink:actuate="onRequest" had been specified. But for:
> 
>   <image xlink:href="foo"/>
> 
> the desired behavior is as if xlink:show="embed" and 
> xlink:actuate="onLoad" had been specified. However there is very little 
> (if any) SVG content that explicitly specifies the XLink 'show' and 
> 'actuate' attributes. Although the SVG 1.0 and 1.1 DTDs make these 
> attributes #FIXED, not all UAs load the DTD, and the next versions of 
> SVG won't have DTDs.
> 
> As well as resolving some of the problems with the use of XLink in SVG, 
> the requested change to the XLink 1.1 WD would explicitly allow other 
> specs to use XLink without requiring authors of their content to know a 
> great deal about XLink, and without requiring them to repeatedly specify 
> the same attributes (show and actuate) with the same values on the same 
> elements over and over.
> 
> I think both of those would be a good thing.
> 
> Best regards,
> Jonathan
> 
Received on Monday, 20 March 2006 23:38:14 GMT

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