Re: A unique ID question ?
W. Eliot Kimber wrote: > > This is why external parsed entities ("external text entities" in SGML > parlance) are evil and should never have been included in XML. Evil or inconvenient, we are stuck with them. The same issues has come up in the DTD for X3D/VRML. Well-formedness and namespaces don't exactly cohere as concepts in practice. For that reason, there was a short consideration to declare them as NMTOKEN. At least, they would weakly validate. If we declare DEF/USE combinations as ID/IDREF: 1. Cannot duplicate DEFs: VRML97 allows this with undefined results. Essentially, in implementation, the last guy declared is used by the next guy. Some authoring tools also flag an error for the author to clean up. 2. Name collisions: Inlines have to be scoped. PROTOS and extenal PROTOS have to be scoped. If one aggregates, one has to declare all of the scopes and validate them individually, or not use ID/IDREF. It is probably better to support the semantics upstream of the broadcast products and keep the client thin as a fashion model. > The only complete and managable solution to this problem is to manage > each component as a complete and independent document and combine them > together *semantically* using something like XLink or HyTime's value > reference facility (explicit use-by-reference as distinct from > hyperlinking). Ensure that any translation or conversion tool uniquefies names where used as IDs. Whether done with Xlink or valuerefs, some means to explicitly spec name resolution is needed. Given the time required to get changes through multiple language ecosystems, my intuition is this will be a problem for a long time. The authoring tools do a lot of work, and while that is not all bad, it should be something developers and customers are more aware of. The features of the tools to manage XML applications are more important to understand than the specification because of the need to validate. That brings up the subject of the number of unicorns required to approve a purchase. For the fresh faces, conformance tests for systems must be spec'd at several levels of the system and normatively declared in the contracts. Remember, contract writers aren't usually deeply technical, so, take time to cover this subject. We had many similar issues with SGML procurements. len 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/ and on CD-ROM/ISBN 981-02-3594-1 To unsubscribe, mailto:majordomo@i... the following message; unsubscribe 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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