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From: Roland Merrick <roland_merrick@uk.ibm.com>
Date: Wed, 4 Jan 2006 11:30:02 +0000
To: Elliotte Harold <elharo@metalab.unc.edu>, public-diselect-editors@w3.org
Cc: w3c-di-wg@w3.org
Message-ID: <OF724CBA81.31EAECCD-ON802570EC.003EB3E6-802570EC.003F2A68@uk.ibm.com>
Greetings, thanks for your comments on the content selection last call 
[1]. The DIWG assigned this comment the identifier Harold-1

This mail documents DIWG's response to your comments.

DIWG Response

DIWG has long recognised the importance of the separation of content and 
presentation. The group's views on the requirements for device 
independence are documented in http://www.w3.org/TR/acdi/. A number of the 
group's members have significant, practical experience of large-scale 
implementations of device independent authoring systems that themselves 
provide separation of concerns.
DIWG is engaged in creation of a number of related techniques that aid 
authors in creating device independent materials. The individual items are 
documented in our charter at 
In particular, in the authoring space, we are pursuing work on physical 
layout of material, semantic enrichment, and mechanisms for aggregation 
and decomposition. The work is focused on creating modules that can be 
added to XHTML Version 2 and XForms, to enhance those specifications for 
situations where authors require to create materials that can be used 
across a variety of devices. However, the group is also engaged in work to 
extend CSS to support, for example, mechanisms for page layout that are 
independent of the page markup. 
DISelect (our preferred acronym for the content selection work) forms just 
a part of this overall profile. 
It is the group's intent that DISelect be available to authors writing in, 
for example, XHTML 2, but it is not the intent that such markup be 
restricted to that use. Consider the task of providing different versions 
of an image for different devices. This is a common requirement in 
situations where transcoding alone gives inappropriate results. In this 
situation, a markup that defines a set of images to be used under 
different conditions could be formed of a host language that includes 
DISelect as a module. A reference to an image from an XHTML 2 object 
element might be resolved by a processor that made the appropriate 
selection between alternative representations using DISelect. In this 
case, the DISelect markup would not be in the document containing the 
XHTML 2 markup itself. Indeed it might not even be in the same system. 
In a similar example, DISelect might be used only to control the inclusion 
of materials from different sources, for example using XInclude. Once 
again, there is the possibility of a clear separation of concerns. 
Sometimes, content selection is required even where the content is itself 
device independent and the reason for using it is not really associated 
with presentation but rather the semantics of the operation. A simple 
example is when the abstract for a news article is sent to a device rather 
than the full text of the article. The most convenient way to arrange this 
may be for there to be a separate resource for the abstract and for the 
article and for contnent selection to be used to determin which is sent. 
Again, in this example, there is no need for the selection markup to be in 
the same resource as either of the forms of the article. 
Experience with practical implementations indicates that there is a real 
need for content selection to be available in a variety of ways to support 
authors in creation of materials that can be used on a variety of devices. 

As with most things, though, such capabilities are open to misuse. 
DIWG agrees with this comment to the extent that we believe it reflects a 
lack of clarity in some of the description. DIWG had hoped that its work 
on its language profile would be sufficiently advanced to allow it to be 
referenced from the DISelect specification. Unfortunately, that has not 
proved to be the case, and the working draft of that work is not yet 
public. In the absence of that document, we propose to:
1.      add comments to the DISelection specification along the lines of 
this response to clarify the intent of the group 
2.      add example(s) where DISelect is used to control use of external 


Regards, Roland
Received on Wednesday, 4 January 2006 13:01:02 UTC

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