XML.com: Standard Data Vocabularies Unquestionably Harmful - 0 views
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At the onset of XML four long years ago, I commenced a jeremiad against Standard Data Vocabularies (SDVs), to little effect. Almost immediately after the light bulb moment -- you mean, I can get all the cool benefits of web in HTML and create my own tags? I can call the price of my crullers <PricePerCruller>, right beside beside <PricePerDonutHole> in my menu? -- new users realized the problem: a browser knows how to display a heading marked as <h1> bigger and more prominently than a lowlier <h3>. Yet there are no standard display expectations or semantics for the XML tags which users themselves create. That there is no specific display for <Cruller> and, especially, not as distinct from <DonutHole> has been readily understood to demonstrate the separation of data structure expressed in XML from its display, which requires the application of styling to accomodate the fixed expectations of the browser. What has not been so readily accepted is that there should not be a standard expectation for how a data element, as identified by its markup, should be processed by programs doing something other than simple display.
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ODF and OOXML are contending to become the Standard Data Vocabulary for desktop office suite XML markup. Sun and Microsoft are proposing the standardization of OpenOffice and MSOffice custom defined XML tags for which there are no standard display expectations. The display expectations must therefore be very carefully described: i.e. the semantics of display fully provided.
In this article Walter Perry is pointing out the dangers of SDV's being standardized for specific purposes without also having well thought out and fully specified display semantics. In ODF - OOXML speak, we would call display presentation, or layout, or "styles".
The separation of content and presentation layer of each is woefully underspecified!
Given that the presnetation layers of both ODF and OOXML is directly related to how OpenOffice and MSOffice layout engines work, the semantics of display become even more important. For MSOffice to implement an "interoperable" version of OpenOffice ODF, MSOffice must be able to mimic the OpenOffice layout engine methods. Methods which are of course quite differeent from the internal layout model of MSOffice. This differential results in a break down of conversion fidelity, And therein lies the core of the ODF interoeprability dilemma!
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There have also emerged a few "horizontal" data vocabularies, intended for expressing business communication in more general terms. One of these is the eXtensible Business Reporting Language (XBRL), about which more below. Most recently, governments and governmental organizations have begun to suggest and eventually mandate particular SDVs for required filings, a development which expands what troubles me about these vocabularies by an order of magnitude.
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