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Pointers model

From: Carlos Iglesias <carlos.iglesias@fundacionctic.org>
Date: Wed, 19 Sep 2007 11:17:51 +0200
Message-ID: <09700B613C4DD84FA9F2FEA5218828190265982F@ayalga.fundacionctic.org>
To: <public-wai-ert@w3.org>

Hi Group,

Here's a new approach to the overall Pointers Model based on the previous model [1], the discussions about it (see thread starting at [1]), and the proposal from Shadi [2].

Pointer (ptr:pointer)
| |-RelatedPointers
| '-EquivalentPointers
|-SinglePointer (ptr:reference)
| |-ExpressionPointer (dc:hasVersion, ptr:expression)
| | |-XPathPointer (ptr:namespace)
| | |-XPointerPointer (ptr:namespace?)
| | |-CSSPointer
| | '-[HTMLPointer]
| |-OffsetPointer (ptr:offset)
| | |-CharOffsetPointer
| | '-ByteOffsetPointer
| |-SnippetPointer (ptr:snippet)
| | |-CharSnippetPointer
| | '-ByteSnippetPointer
| '-LineCharPointer (ptr:line, ptr:char)
'-CompoundPointer (ptr:startPointer)
   |-StartEndPointer (ptr:endPointer)
   |-StartOffsetPointer (ptr:offset)
   | |-StartCharOffsetPointer
   | '-StartByteOffsetPointer
   |-StartSnippetPointer (ptr:snippet)

The differences with Shadi's proposal are basically:

- Everything is a Pointer (PointerGroups included). I think that, regardless of our needs within the group, if we want people reusing the pointers this is the best approach (we shouldn't force people to use PointerGroups every time they want to use a Pointer). Additionally I don't see any benefit in separating PointerGroups from the rest of Pointers.

- It uses StartCharOffsetPointer and StartByteOffsetPointer instead a generic StartOffsetPointer that makes use of the Single OffsetPointers to avoid the duplication of ptr:reference (startPointer and OffsetPointer) that may give way to inconsistence if they are different (a CompoundPointer should exist only within a unique resource).

- The same as above with StartSnippetPointers

That leads us yet to one issue: we have yet a duplication of ptr:reference that could lead to inconsistence in StartEndPointers as startPointer and endPointer are both SinglePointers. We have a similar problem with EquivalentPointers

Any thoughts?

[1] - [http://lists.w3.org/Archives/Public/public-wai-ert/2007Jul/0042.html]
[2] - [http://lists.w3.org/Archives/Public/public-wai-ert/2007Jul/0049.html]



Carlos Iglesias

CTIC Foundation
Science and Technology Park of Gijón
33203 - Gijón, Asturias, Spain

phone: +34 984291212
fax: +34 984390612
email: carlos.iglesias@fundacionctic.org
URL: http://www.fundacionctic.org
Received on Wednesday, 19 September 2007 09:17:29 UTC

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