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So now we would have a Schema-Lite? Sounds like XDR. The notion of using different schemas at different points in production is a good concept and was valid even when only DTDs were used. A lot of the work on modularity prior to webSGML arose from the notion that one needed base modules from which one could assemble DTDs for different stages of production, restricting and relaxing rules at each stage. There was also fancy work with OR grouped DTDs to enable the editors to take advantage of bottom-up definitions. As to having different schema languages, that is a bit tougher because now one gets a fatter object framework and that is a maintenance/cost problem. My opinion is that until the designers get more practice with using XML Schemas, working out modular designs, and adding rule constraints such as normatively might be created with XSLT sheets and practically with Schematron, it is too early to look at alternatives. Cost is the driver. Len http://www.mp3.com/LenBullard Ekam sat.h, Vipraah bahudhaa vadanti. Daamyata. Datta. Dayadhvam.h -----Original Message----- From: Rick Jelliffe [mailto:ricko@a...] This last one is worth keeping in mind, it may be that each stage in an information flow is optimal for a different schema language (or paradigm!). So if one has limited resources, one probably picks whichever schema language or paradigm will have the broadest impact, knowing the solution is less than perfect in each stage. But if one has a few more resources, creating stage-dependent schemas might be worthwhile. For example, one might have one DTD for accepting data from contractors and data conversion houses, but a much stricter one for new documents created -house. Or you might use XML Schemas for autogenerating Java interfaces, but use Schematron to check that incoming data is consistent with more complex rules. Or you might use RELAX for your XSL validation, but DTDs for the resulting documents. I don't expect there will many people using XML Schemas -and- RELAX -and XDR/SOXetc. in the same house. Personally, I find it very difficult to keep different grammar conventions in mind. Perhaps we need a "Common Structures" proposal, which would provide the union of XML Schemas and RELAX NG, probably using XML Schemas syntax. Like RELAX Core, I guess. Kawaguchi-san's article on XML.com is probably a good place to start (without endorsing it.) Any volunteers?
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