[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: When is an attribute an attribute?
Roy Tennant wrote: > > I've been trying to figure this out for a while with no success. It seems > to me that there are several quite different ways one can encode > information in XML. Are all of the following correct? Yes. > When and why would > you choose one over another? Does it matter? Thank you for your indulgence > as I puzzle out what must surely be readily apparent to most of you. Ok, a DTD really helps this sort of discussion along, but FWIW: > Example 1: > --------- > > <BOOK TITLE="The Call of the Wild" AUTHOR="London, Jack"\> Use empty elements and attributes for tag bags, basically, if the datum has no frequency and order requirements (only occurs once somewhere in the attribute list). NOTE: I haven't looked to see if XML dropped the SGML restriction on repeated values in attlist decls. > Example 2: > --------- > > <BOOK AUTHOR="London, Jack">The Call of the Wild</BOOK> Use this if you don't care that the string inside the tags is only differentiated by the BOOK, that is, semantically, there is no difference between this and <BOOK AUTHOR="London, Jack">Love that Wolf!!</BOOK> or IOW, your application has to know that is a title. > Example 3: > --------- > > <BOOK> > <TITLE>The Call of the Wild</TITLE> > <AUTHOR>London, Jack</AUTHOR> > </BOOK> Use this when it is important to know there is a title and author (i.e, this BOOK HAS-A TITLE, HAS-A AUTHOR; the string, The CALL of the WILD IS-A TITLE). Given the element type declaration, you can tell which order they should come in, are there multiple authors, are there alternate titles, etc. The semantic is application dependent. For a linking semantic, you might be counting nodes inside the BOOK. For rendering, you might be assigning the font value based on the context of the book element. 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/ 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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