Re: Mixed Content Models
[Jerome McDonough] > In looking over the XML spec (3.2.2) on mixed content models, > something isn't clear to me. I'm hoping someone here can enlighten > me. > > I've inherited a DTD for development that was originally > intended to be an SGML DTD, and has been converted to XML. > Contained within it is the following: > > <!ELEMENT qstn (#PCDATA | (preQTxt?, qstnLit?, postQTxt?, forward?, > backward?, ivuInstr*))* > > Is this a legitimate content model under XML section 3.2.2? No. See production . A mixed content declaration MUST be of the forms <!ELEMENT e-type1 (#PCDATA | sub1 | sub2 | sub3)*> <!ELEMENT e-type2 (#PCDATA)> This is not optional. > Msxml doesn't have a problem with it, and nsgmls using the -wxml > flag also happily parses the DTD. IBM's xml4j, however, complains: > "Codebook.dtd: 1256, 33: This content model is not matched with the > mixed model '(#PCDATA|FOO|BAR|. . .|BAZ)*': '(#PCDATA|(preQTxt?, > qstnLit?, postQTxt?,forward?,backward?,ivuInstr*))*". I'm a little surprised that nsgmls doesn't catch this; however, the -wxml option warns about some, or even most, XML errors, but not all of them. Fortunately, your content model is equivalent to <!ELEMENT qstn (#PCDATA | preQTxt | qstnLit | postQTxt | forward | backward | ivuInstr)*> so this isn't a real problem. In some cases, it is true that content models will need to be either tightened or loosened to be expressed as XML (notably models involving exceptions). -Chris -- <!NOTATION SGML.Geek PUBLIC "-//Anonymous//NOTATION SGML Geek//EN"> <!ENTITY crism PUBLIC "-//O'Reilly//NONSGML Christopher R. Maden//EN" "<URL>http://www.oreilly.com/people/staff/crism/ <TEL>+1.617.499.7487 <USMAIL>90 Sherman Street, Cambridge, MA 02140 USA" NDATA SGML.Geek> xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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