[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Inheritance in XML [^*]
Jon Bosak wrote: > > The people who complain that XML does not have clearly > defined semantics mean "semantics" the way I do -- as a synonym for > "meaning". They are concerned that the meaning of a construction like > > <PATIENT_NAME>Jones~Jane</PATIENT_NAME> > > is not completely clear in the absence of a healthcare industry > standard like HL7 PID. What I was saying is that the meaning of such > a construction taken by itself is not just unclear, it really isn't > there at all. Well, here I am off being the theorist again. Just like you, I use semantics and meaning interchangably also (at least I think I do). If you've taught an XML course recently, I'll bet you find yourself saying: "this syntax *means* that..." (e.g. "The start tag means that an element has begun.") That's because there are several levels of meaning. You use this example: <PATIENT_NAME>Jones~Jane</PATIENT_NAME> At the XML Spec level the text models an abstraction like this: OBJECT-TYPE=Element TYPE-NAME="PATIENT_NAME" ELEMENT-ATTRIBUTES={} ELEMENT-CONTENT="Jones~Jane" At a level above that, (let's say HyTime), it might mean: OBJECT-TYPE=HyperLink LINK-TYPE=NameLoc TARGET-NAME="Jones~Jane" At a level above that, (let's say HL7) it might mean: OBJECT-TYPE=Patient Reference TARGET={ a particular referenced element } In a particular hospital, it might mean: OBJECT-TYPE=Patient Reference TARGET={ an object representing the database record described by the referenced element } I know the XML WG went to a lot of work to try and leave semantics out, but if we can agree that XML specifies the first level of meaning, then we agree that XML specifies base-level semantics. As long as we agree on that, we might as well make those semantics precise in the next iteration, as SGML will do in its next iteration (after 10 years of trying to get away without it). Paul Prescod - http://itrc.uwaterloo.ca/~papresco "Perpetually obsolescing and thus losing all data and programs every 10 years (the current pattern) is no way to run an information economy or a civilization." - Stewart Brand, founder of the Whole Earth Catalog http://www.wired.com/news/news/culture/story/10124.html 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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