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-----Original Message----- From: Paul Prescod <papresco@t...> To: xml-dev@i... <xml-dev@i...> Date: 11 January 1998 15:50 Subject: Re: Embedding Content as Element Content or As An Attribute Value Paul Prescod wrote, inter alia: >I'm surprised, though that you would claim that the distinction between >"hasproperty" and "containsobject" is missing in every ontological >system you are aware of. That distinction is certainly one of the traditional difficulties of all data modelling, and thanks, yes, it's helpful to see it in those terms. But I don't think the XML/SGML distinction between attributes and content is quite the same. If we consider the difference between: <PIZZA PRICE="$12.00" DESC="Ham and mushroom"/> versus <PIZZA PRICE="$12.00">Ham and Mushroom</PIZZA> then the distinction is not between an attribute and a contained object, but between "ordinary" attributes and one "special" attribute which we call the content of the object. The ontological systems I am aware of do not treat one of the attributes of an object as being special in this way. In fact the representation I am using is more like: <PIZZA> <PRICE>$12.00</PRICE> <DESC>Ham and mushroom</DESC> </PIZZA> In other words, I am treating all the attributes as "contained objects", and the reason I am doing this is that in my particular domain, some of the attributes may carry additional information (sometimes called "facets") e.g. where did this information come from, how reliable is it, and when did it last change. I apologize for my faux-pas in the suggestion that the scope of application of XML was wider than that of SGML. I had forgotten, of course, that to SGML insiders SGML is applicable to everything - it is only outsiders who draw boundaries around it :-) PS: can I ask for some advice? In my DTD for the above, I want to say that the element PIZZA has no immediate character content other than ignorable white space. I feel sure it must be possible to say this, but I haven't found out how. The alternative seems to be disallow character content entirely, and generate documents using a layout such as: <PIZZA ><PRICE>$12.00</PRICE ><DESC>Ham and mushroom</DESC ></PIZZA> but I find it hard to believe this is what the designers intended. Mike Kay 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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