[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Commentary on DCD
Here are a few tentative comments on the DCD proposal. I am writing from my experience developing XSchema, but I am not writing *for* the XSchema team. 1. The Description and Value properties seem to extend the RDF syntax in ways not warranted by the current RDF draft (more bluntly: "are erroneous RDF"). The value of these properties is evidently a Resource which is encapsulated within the property element. An example appears in clause 3.4.2 of DCD. However, the RDF syntax in the current draft (1998-07-20) supports only three kinds of content for property elements: #PCDATA representing the string value of the property, a container element as value of the property, and an RDF:Description element serving as a proxy object. There are no provisions for embedding arbitrary mixed content and calling that the value of the property: data can't go inside metadata, roughly speaking. To make Content and Value conform to the current draft, they would need to be pulled out of the RDF part of the document altogether, tagged with an ID attribute, and referred to from within the RDF using <DCD:Value about="#the-id"> or the like. Clause 2.1.1 is silent on this extension to RDF. 2. Based on XSchema discussions, I believe that more suitable values for the Root property would be "Recommended", "Unlikely", and "Forbidden" or the like. Distinguishing between "Recommended" and "Unlikely" assists authoring tools in limiting normal use of document roots without constraining abnormal but still permissible uses, thus furthering design principle 3. 3. The DCD draft is totally silent about notations, in violation of its own design principle 1 (clause 1.2) Although notations are not part of namespaces, they are still an important factor in XML. Perhaps as a consequence, the datatype "notation" in clause 4.1 fails to provide for the list of legal notations that the XML attribute-type model requires: there are no XML attributes of type "notation" simpliciter. 4. The list of primitive datatypes is still too long and cluttered. Id, idref, and idrefs are really NAME and NAMES with the separate id-roles property. Fixed-point values should be represented with a denominator property rather than the less general (decimal) scale. General rational numbers need support (353/113, e.g.). The various forms of date-time are clutter: there should be only one kind of timestamp, useless SQL specifications notwithstanding. All the i2, i4, etc. etc. are just values of max and min. There is no way to represent the difference between exact and inexact values. (Yes, I know I'm making work for everyone.) -- John Cowan http://www.ccil.org/~cowan cowan@c... You tollerday donsk? N. You tolkatiff scowegian? Nn. You spigotty anglease? Nnn. You phonio saxo? Nnnn. Clear all so! 'Tis a Jute.... (Finnegans Wake 16.5) 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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