[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Integrity in the Hands of the Client
> From: Paul Prescod <papresco@t...> > > > "Sometimes the actual claims for markup-based systems are overstated; > the claim that SGML results in portable documents, for example, > falls afoul of the observation that it is possible to put angle > brackets around troff tags, supply a simple document type descrip- > tor,and thereby achieve anSGML-compliant document, without gaining > any portability or descriptiveness for the information. True > portability requires not only that informa- tion be transportable > from one machine to another,but that the semantics of that informa- > tion be the same on either machine. SGML, in particular,claims to > transfer no semantics, so it surely cannot guarantee portability." > > [1] "Markup Reconsidered" http://www.sil.org/sgml/raymmark.ps Without wishing to disagree in any way with Paul, the quote is perhaps not quite true, I think. Sticking angle brackets on troff code may give you a document that is syntactically *valid* SGML but, because to the extent that it uses elements to markup processing instructions, the document does not *conform* to SGML. Such conformance cannot be judged mechanically, but by looking at the definitions in ISO 8879 for processing instructions and elements. People often seem to think "SGML is a grammar; I can markup all sorts of sloppy things; therefore SGML is a bad grammar". But SGML is more than a queer grammar, it is a language: the terms "element" and "processing instruction" (etc) have broad but useable meanings. I think one problem with XML is that these definitions of what an element, etc., actually mean are not present. XML *is* just a grammar, more or less. But to convert it to a useful language, we often have to plug in SGML's definitions. And again, we shouldn't then think that in all cases "SGML conformance=good; SGML non-conformance=bad". But that is separate from "do I need SGML validity? do I need XML well-formedness? do I need a custom syntax?". Rick Jelliffe 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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