[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: XSchema Spec Section 2.3, Draft 1
Simon St. Laurent wrote: > > John Cowan wrote: > >That was my original design. Ron thought it was clearer to allow > >an explicit PCData element equivalent to an empty Mixed element, > >and I acquiesced. > > For now, I'll leave it. Ron's away for a couple of days, and we can discuss > it when he gets back. I'm back. The caves in France found me unpalatable and spat me back to the surface. Many DTDs have lots of PCDATA-only elements, so I included the PCData element as a clear, convenient shorthand. That is, I found: <ElementDecl id="foo"> <PCData/> </ElementDecl> to be clearer than: <ElementDecl id="foo"> <Mixed/> </ElementDecl> This is particularly true when you are transmitting non-document data such as corporate or scientific data. For example, a simplistic sales order DTD might be: <!ELEMENT SalesOrder (Number, CustomerNumber, Date, Line+)> <!ELEMENT Number (#PCDATA)> <!ELEMENT CustomerNumber (#PCDATA)> <!ELEMENT Date (#PCDATA)> <!ELEMENT Line (PartNumber, Quantity)> <!ELEMENT PartNumber (#PCDATA)> <!ELEMENT Quantity (#PCDATA)> Note that everything resolves very quickly to PCDATA -- it's just text, numbers, and dates and contains no embedded markup such as bolds or jumps or what-have-you. There is nothing "mixed" about it. The PCData element, while not strictly necessary, allows you to get this notion across quite easily. (Note also that I considered a Scalar element instead of a PCData element. With a Type attribute -- initially allowing PCDATA only -- we could expand into typing in the future, which the database community really needs.) By the way, I like the fixed frequency of ZeroOrMore on Mixed. -- Ron Bourret 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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