Re: DTD Files !
David Carlisle is correct that XSL can be used for many kinds of validation, more kinds in fact than DTDs. One of its advantages in such cases is that it can do a kind of "loose" validation, as opposed to being just a "go/no-go" gauge, which is what DTDs amount to (either the document conforms, or it doesn't). Nevertheless, there are cases where DTDs are very useful (and I don't think David has tried to make the argument that DTDs are never useful -- only that XSL, and/or other validation techniques, can be used for many types of validation). One thing DTDs are useful for (that other contributors to this thread have mentioned) is the configuration of a structured editor, which actually constrains the user's data entry to assure that anything created will conform to the necessary model. When using such an editor, only elements and attributes explicitly allowed by the DTD can be inserted in a given place. Especially when non-experts in XML or the document model are writing content, and when documents are large and complex, this is *much* easier than creating the stuff and then doing validation on it in batch mode (whether by using a DTD or by another method). So far I haven't seen a structured editor that can use XSL validation like this. Actually an XSL stylesheet would be a pretty difficult thing to wire into this type of application (if not impossible), although I dare say the schemas that Rick Jelliffe's Schematron uses to build its stylesheets (or a subset of them), might work. When XML Schema is done, it's expected one of its common use cases will be for this kind of thing. So far, the only editors I know of that work like this (XMetaL, Excosoft Documentor, Arbortext, WordPerfect etc.) all start with DTDs. Another thing DTDs are useful for, in my experience, is in learning XML, since they can give a good sense of the structuring possibilities of the language -- something quite new, for example, to HTML users. But this is really out of scope for this list -- it should really be on XML-L, where probably a greater portion of the readership would find it useful or interesting. --Wendell ====================================================================== Wendell Piez mailto:wapiez@xxxxxxxxxxxxxxxx Mulberry Technologies, Inc. http://www.mulberrytech.com 17 West Jefferson Street Direct Phone: 301/315-9635 Suite 207 Phone: 301/315-9631 Rockville, MD 20850 Fax: 301/315-8285 ---------------------------------------------------------------------- Mulberry Technologies: A Consultancy Specializing in SGML and XML ====================================================================== XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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