Safe Plurality: Can it be done using OOXML's Markup Compatibility and Extensions mechanism? - O'Reilly Broadcast - 0 views
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During the OOXML standardization proceedings, the ISO particpants felt that there was one particular sub-technology, Markup Compatibility and Extensibility (MCE), that was potentially of such usefulness by other standards, that it was brought out into its own part. It is now IS29500:2009 Part 3: you can download it in its ECMA form here, it only has about 15 pages of substantive text. The particular issue that MCE address is this: what is an application supposed to do when it finds some markup it wasn't programmed to accept? This could be extension elements in some foreign namespace, but it could also be some elements from a known namespace: the case when a document was made against a newer version of the standard than the application.
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Rick Jelliffe posts a frank view of the OOXML compatibility framework, a document I've studied myself in the past. There is much that is laudable about the framework, but there are also aspects that are troublesome. Jelliffe identifies one red flag item, the freedom for a vendor to "proprietize" OOXML using the MustUnderstand attribute and offers some suggestions for lessening that danger through redrafting of the spec. One issue he does not touch, however, is the Microsoft Open Specification Promise covenant not to sue, a deeply flawed document in terms of anyone implementing OOXML other than Microsoft. Still, there is so much prior art for the OOXML compatibility framework that I doubt any patent reading on it would survive judicial review. E.g., a highly similar framework has been implemented in WordPerfect since version 6.0. and the OOXML framework is remarkably similar to the compatibility framework specified by OASIS OpenDocument 1.0 but subsequently gutted at ISO. The Jelliffe article offers a good overview of factors that must be considered in designing a standard's compatibility framework. For those that go on to read the compatibility framework's specification, keep in mind that in several places the document falsely claims that it is an interoperability framework. It is not. It is a framework designed for one-way transfer of data, not interoperability which involves round-trip 2-way of exchange of data without data loss.
