Understanding RDF

Paul Prescod paul at prescod.net
Mon Jan 25 07:55:45 GMT 1999

I keep thinking I understand RDF and then I look at DCD and think "I 
guess I don't." DCD is supposed to be an RDF vocabulary, right? I know
that it uses some extensions to RDF (argh!), but even so, I don't see
how it works.

Rdf :: = [ <rdf:RDF> ] description * [</rdf:RDF>]

It is odd to me that the RDF wrappers are optional and that not even an 
RDF identifying attribute or processing instruction is required, but okay 
let's presume that we "know" that a DCD is an RDF and have just left off 
the wrapper elements. That means that the root DCD element is a 

description ::= typedNode
typedNode ::= <typeName ...> property* </typeName>

But DCD says

DCD ::= <DCD> elementDef * </DCD>

(I presume...I can't actually find a grammar in the DCD spec. but I 
haven't looked hard...it certainly isn't in the table of contents)

So what are the properties of the DCD node? Just ElementDef and
Am I to understand that these are vector-valued properties?

People complain about SGML minimization, but RDF abbreviation is much 
more complicated. Perhaps someone can walk me through the expansion of 
A DCD document into completely described nodes and properties.

 Paul Prescod  - ISOGEN Consulting Engineer speaking for only himself

"You have the wrong number."
"Eh? Isn't that the Odeon?"
"No, this is the Great Theater of Life. Admission is free, but the 
taxation is mortal. You come when you can, and leave when you must. The 
show is continuous. Good-night." -- Robertson Davies, "The Cunning Man"

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