[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: When is an attribute an attribute?
-----Original Message----- From: len bullard <cbullard@h...> > The funniest thing I've seen lately is a statement > on the Microsoft XML site that XML gets rid of > committees who design DTDs in favor of a > more "organic" approach. Lots of luck. ;-) :-) My book <plug type="shameless">The XML & SGML Cookbook</plug>, due out next month, looks at this issue. In particular it gives some basic patterns and considerations that can be used for "rapid prototyping" a document type. Most document types require some rethought after deployment. Very few people actually have much of an idea of what their data contains. Anyway, when you start actually using markup systems you will want to make maximal use of the particular tools you have bought. So even if a DTD was created without any consideration of the software to be used, there is often good reason to enhance the DTD to make best use of the particular capabilities of the appliciations (and to overcome flaws that turn up). DTDs made by committees often tend to be rather kitchen-sinkish. But this is better dealt with by dividing them into separate DTDs (especially for front and backmatter), which are more manageable, or by introducing "training-wheel" DTDs which won't scare people off, rather than by saying they are over-engineered. Documents and publications are much more complicated than people want to accept: sometimes the only way is for people to learn by being given a simple DTD and then having issues in their documents prove to them that a larger DTD is actually what they require. "Organic" is an attractive word. Being able to make ad hoc changes to DTDs is great if you are processing them, or if you have a family of documents which are similar but not exactly the same type. SGML systems have suffered in the past because DTD-alterations was often a large-scale exercise for gurus. XML is doing good things in making this more difficult. But the idea that XML markup declarations are inherently inflexible, while declaration-less XML allows more "organic" development is spurious. One trick SGML people use (this is adapted from Travis and Waldt's book) is to make explicit element types for unaccounted-for elements. This gives you somewhere to park important data in the absense of DTD elements. This kind of flexibility is available in any DTD: you don't need to abandon XML markup declarations to get it. For example, the following declaration is a good basis for such an element type: <!ELEMENT new ANY > <!-- "class" is the name the user might suggest for this element type if in a DTD. "HTMLform" is the nearest HTML element type, to help rendering. --> <!ATTLIST new id ID #IMPLIED class CDATA #REQUIRED HTMLform CDATA #IMPLIED comment CDATA #IMPLIED> ... <new class="dog" HTMLform="em">Rover</new> (Check out the HTML span and div elements too.) 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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