Re: Newbie Q
>Is there a formal rule for the use of Atrributes vs Elements? The >assumption I am going on (per The XML Primer) is that Attributes are >best used to communicate information to the browser/application, and >Elements are best used for actual Data. Is this a valid assumption? > >In an EDI transaction, I was going to put the Header and Trailer >information in attributes, with the actual Detail Segments as >Elements... > >Any thoughts? There are also practical issues I guess. If you need to validate the document with a DTD, there is much more control available to control the content of subelements. You can say that the parent element's content model allows this or that, or this, that or the other, etc... With attributes, there is less flexibility. Each attribute is either there or not. There is no way to indicate that if you provide this one, you can't provide that one, or if these two are present, then you can't have that one, or if this one is present, then that one has to also be present, and so on (at least there is no way that I know of :-) Beyond that I think its purely an issue of what works best for what you want to do. And there is sometimes an issue of readability and writeability if the documents are ever dealt with by actual humans <gasp> :-) Attributes with large values are kind of funky (IMHO) to make very readable, so I'd make any property that could have large values an element if all other things were equal (which of course they often aren't.) Overall, I guess the best rule of thumb is that attributes should hold stuff that either you need to get to fast without wanting to iterate the sub elements, or which provide 'control information' as you indicated, or which need to have ID/IDREF semantics enforced, or that you might want to provide implicit defaults for, and probably some others that I can't think of :-) ---------------------------------------- Dean Roddey Software Weenie IBM Center for Java Technology - Silicon Valley roddey@u... 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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