Cart
[Home] [By Thread] [By Date] [Recent Entries]
At 2009-11-14 21:55 -0500, I wrote: >There may be other "core" faults, but that is one that has been a >problem for me. Of course I thought of another one right after I posted the above, a fault that is a deficiency rather than something broken (though you could consider the specification broken without the functionality): W3C Schema validation semantics cannot express the constraints of XHTML's "head" element which in DTD-speak is: <!ENTITY % head.misc "SCRIPT|STYLE|META|LINK|OBJECT" -- repeatable head elements --> <!ENTITY % head.content "TITLE & BASE?"> <!ELEMENT HEAD O O (%head.content;) +(%head.misc;) -- document head --> The problem is with the limited cardinality of "title" and "base" and the arbitrary order of elements preventing the use of alternation because of the ambiguous content models. In RELAX-NG the interleave concept addresses this. And yet another fault of 1.0 that will be addressed with 1.1 is mutually-exclusive attributes, which is needed if one wanted to express W3C XSL-FO using a schema (for <basic-link> one has either internal-destination= or external-destination= but not both and not neither). And I believe 1.1 doesn't address this with a semantic expressing the exclusivity as an operator with operands, but with an assertion after the fact that the presence of both is unacceptable. In RELAX-NG attributes and elements can both be operands in the constraint semantics. So these are but two examples of W3C specifications of XML vocabularies that existed before the W3C Schema specification was finalized, where each one has document constraints that cannot be expressed by W3C Schema semantics. Other posters in this debate have cited new W3C specifications that are using RELAX-NG instead of W3C Schema, and I doubt the reason they used it was because of the size and complexity of W3C Schema. If they are XML experts, they can make their way through specifications of any size to look for what they need. I suspect the decisions were based on deficiencies in the validation semantics required for their needs. Again, I hope this is considered helpful to the debate. . . . . . . . . . Ken -- Vote for your XML training: http://www.CraneSoftwrights.com/x/i/ Crane Softwrights Ltd. http://www.CraneSoftwrights.com/x/ Training tools: Comprehensive interactive XSLT/XPath 1.0/2.0 video Video lesson: http://www.youtube.com/watch?v=PrNjJCh7Ppg&fmt=18 Video overview: http://www.youtube.com/watch?v=VTiodiij6gE&fmt=18 G. Ken Holman mailto:gkholman@C... Male Cancer Awareness Nov'07 http://www.CraneSoftwrights.com/x/bc Legal business disclaimers: http://www.CraneSoftwrights.com/legal
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] |
