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Re: SVG12: A.7.15 id attribute

From: Bjoern Hoehrmann <derhoermi@gmx.net>
Date: Mon, 02 Jan 2006 00:24:30 +0100
To: Robin Berjon <robin.berjon@expway.fr>
Cc: www-svg@w3.org
Message-ID: <66ogr1plc3tv8e56ubrca8k9a8an3rba7i@hive.bjoern.hoehrmann.de>

* Robin Berjon wrote:
>>   http://www.w3.org/TR/2005/WD-SVGMobile12-20050413/svgudom.html
>> appendix A.7.15 is unclear about the value of the id attribute if an
>> element uses both the id and the xml:id attribute on the same element
>> (which is not allowed but not covered by error handling rules either)
>> and, worse, which of these attributes are affected by setting it. It
>> seems that setting it would only affect the xml:id attribute as that
>> is recommended for new content, please change the draft to this effect.
>> Please change the draft to be clear about the value if both xml:id and
>> id are used on the same element.
>
>The notion that having both id and xml:id on a single element was not 
>allowed was an editorial oversight as we had already resolved that it was.
>
>Concerning the behaviour of having both attributes with different 
>values, notably concerning the way they impact the id field on 
>SVGElement the behaviour has now been specified with the required 
>precision, with additional details regarding other DOM interactions. 
>Setting the id field updates both attributes so that they can be kept in 
>sync.

My reading of the xml:id Recommendation is that the attribute values
must be unique as opposed to uniquely identify an element, so keeping
them in sync would actually trigger xml:id errors. So to accept this
there would need to be normative errata to the xml:id Recommendation
that changes this constraint.

The new text notes 

  when both 'id' and 'xml:id' are specified on the same element but
  with different values, the resulting behaviour is unspecified and
  implementation-dependent. It is however recommended that whenever
  possible, implementations should give precendence to the 'xml:id'
  attribute. 

I don't really understand what this means, e.g., which behavior is
referred to here or what giving precedence to the xml:id attribute
would mean. The intent might be to say that the SVGElement::id
attribute must return either the value of the id or the xml:id
attribute and should return the value of the xml:id attribute. But
it might refer to something else entirely.
-- 
Björn Höhrmann · mailto:bjoern@hoehrmann.de · http://bjoern.hoehrmann.de
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Received on Sunday, 1 January 2006 23:24:24 GMT

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