Notes on ADC SC Call - 2nd August 2011

[Robin LaFontaine <robin.lafontaine@deltaxml.com>]

Notes on ADC SC Call - 2nd August 2011

Present
-----------
Robin LaFontaine (Chair)
Doug Mahugh
Tristan MItchell
Rob Weir
Ben Martin
John Haug
Dennis Hamilton
Svante Schubert

Robin introduced the meeting saying that the purpose was to review the use cases to enable better understanding of the strengths and weaknesses of each approach. We have both ECT and GCT solutions for UC1, UC2 and UC3 to date, so discussion would focus on these.

Some ideas to focus discussion:
  - Does it represent the change correctly?
  - Is it unambiguous?
  - Does it include in the change data that has NOT changed?
  - For multiple changes: if conceptually they can be undone in an arbitary order, is that possible with this representation?


UC1
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Robin asked about the use of formnat-change-start format-change-end tags in both the body of the document as well as to mark added styles.
Could the styles use an attribute rather than the wrapper?
i.e. why not instead of this:
    <ct:format-change-start ct:id="1" />
    <style:style style:name="NormalStyle" style:family="text">           
      <style:text-properties fo:font-weight="normal" />
    </style:style>
    <ct:format-change-end ct:id="1" />
use this:
   <style:style ct:id="1" style:name="NormalStyle" style:family="text">   
     <style:text-properties fo:font-weight="normal" />
   </style:style>

John mentioned that there was no requirement for using the same wrapper in both places (i.e. a different wrapper could be used for style addition for example) but that one of the core principals of ECT is that existing element definitions are not affected by change-tracking. All change-tracking is marked by new, specific elements.

Some discussion about what is allowed between a change-start and a change-end element and whether these both need to have the same parent element - John said there were no rules about this. The implications of this have not been thought through yet, but splitting change-start and change-end across element boundaries is a known problem in current ODF change-tracking.

Robin asked why the ECT does not have a way of representing attribute change.
John said that the previous answer applies to this as well, and the intention is to handle this the same way as current ODF change-tracking.

Noted that ECT seems to be able to add/delete spans and adjust span attributes without add/delete of content and so perhaps the same technique can be used for list levels and other areas. It seems inconsistent as it stands.

On the 'bucket' design ....

Ben mentioned that UC7 and UC8 (that he proposed) give examples of where the bucket design can cause problems. This is a particular issue when cacheing elements that contain and xml:id. How is the uniqueness maintained?
Bookmark start and end tags can also be problematic if they are located in such a way that a cached bucket contains only one of the markers. It then becomes more complicated to pair them up correctly.

Robin asked if the ECT bucket design is similar to the way that OOXML change-tracking works.
John replied that OOXML and ODF are structured in a very different way and so it is hard to compare ECT buckets with OOXML change tracking.
In that respect, it is difficult to say whether ECT or GCT would be easiest to implement in MS Word.

UC2
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In ECT, this is marked as an insert/delete (as opposed to a similar markup to the format change) because of the structural change involved. Simplest approach is the bucket 'cache and replace'.

Ben asked whether it would be possible in GCT to amend the spec so that more than one level of hierarchy could be removed within a single delta:remove-leaving-content-start element.

UC3
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No further comments


UC7 and UC8
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It was agreed that UC7 and UC8 would be added to the list of detailed examples.
John and Tristan are to provide example markup for those use cases that remain to be completed for the ECT and GCT respectively.

Next Steps
------------
Progress over past few months seems slow and we still have two candidate proposals.

Use case study needs to continue and specifically:
ECT solutions needed for [UC4, UC5, UC6 -these have been completed 3 Aug 2011] UC7, and UC8
GCT solutions needed for UC7 and UC8

We will have another call in mid-Sept, John will tell Robin when his is available.

If the SC needs to refer this back to the TC for a decision, Rob says that a Consensus Report would be needed (a few pages) to inform their decision because they could not look at all the documents. Robin agreed to start work on this to focus our discussions.

-- 
-- -----------------------------------------------------------------
Robin La Fontaine, Director, DeltaXML Ltd  "Change control for XML"
T: +44 1684 592 144  E: robin.lafontaine@deltaxml.com      
http://www.deltaxml.com      
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