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Welcome to the world of design by committee. You can say the exact same things about C99, C++ and SQL92 which have had 3, 5 and 10 years respectively for smart people to implement but still are full of quirks, issues and distinctions between competing implementations. I'm sure more experienced and knoowledgeable people than me can add more names to this list (perhaps CSS and HTML?) -----Original Message----- From: Paul Spencer [mailto:paul.spencer@a...] Sent: Wed 3/20/2002 3:06 AM To: Eric van der Vlist; xml-dev@l... Cc: Subject: RE: Who can implement W3C XML Schema ? > I begin to be really worried about the "implementability" of W3C XML > Schema and I'd like to give an example of what I have already > experienced several times in the past months (I insist that this is an > example and almost the general case, *not* an exception). I have to agree. I keep coming across schemas that validate in one tool, but not in another. Sometimes the schema is valid but wrongly described as invalid, other times it is invalid but the errors are not detected. In one case, I was asked to look at a schema, and a tool detected an error, but missed the identical error elsewhere in the same file. I have yet to find any tool that correctly identifies all errors without also indicating false errors. And this is on relatively simple schemas. We do a lot of schema development and test all schemas against three of the popular validating tools before delivery. This way we try to catch the errors and to work around the constructs that generate false errors. But, of course, many here will be aware of one particular tool that gives different false errors depending on whether you are looking at the schema in a graphical view or as text. They don't make it easy for us ... The guys that write these tools are not stupid. If they haven't got it right by now, I worry for the future of XML Schema. Paul Spencer CTO, alphaXML Ltd Author: Professional XML Design and Implementation (Wrox Press) Co-author: Beginning XML, Professional XSL (Wrox Press) XML services for Industry and Government +44 (0)1491 630053 http://www.alphaxml.com ----------------------------------------------------------------- The xml-dev list is sponsored by XML.org <http://www.xml.org>, an initiative of OASIS <http://www.oasis-open.org> The list archives are at http://lists.xml.org/archives/xml-dev/ To subscribe or unsubscribe from this list use the subscription manager: <http://lists.xml.org/ob/adm.pl>
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