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Difficulty with syntax specification

From: Graham Klyne <gk@ninebynine.org>
Date: Fri, 09 Jul 2004 10:38:10 +0100
Message-Id: <5.1.0.14.2.20040709102336.0335c980@127.0.0.1>
To: RDF comments <www-rdf-comments@w3.org>

I am finding a difficulty with the RDF syntax specification:
   http://www.w3.org/TR/2004/REC-rdf-syntax-grammar-20040210/

In section 6, the document indicates:
[[
There is no mapping of the following items to data model events:

processing instruction information item
unexpanded entity reference information item
comment information item
document type declaration information item
unparsed entity information item
notation information item
namespace information item

Other information items and properties have no mapping to syntax data model 
events.
]]

Except that it also states:
[[
All information items contained inside XML elements matching the 
parseTypeLiteralPropertyElt production form XML literals and do not follow 
this mapping. See parseTypeLiteralPropertyElt for further information.
]]

This makes the specification, as stated, a real pain to implement, because 
it is not possible to separate the preprocessing from infoset to the syntax 
data model events from the syntax analysis itself (as it is necessary to 
parse the syntax data model events in order in order to determine which 
parts of the infoset are not processed to events).

...

A consequence of this is that I shall not be implementing XML literals as 
specified in my initial RDF/XML parser implementation, because I find 
(having otherwise followed the syntax specification processing description) 
the contortions and additional effort needed just don't seem to be 
justified by what I feel is, in practice, a very marginally-useful feature 
of RDF/XML.

...

In hindsight, it seems to me that we might have done better to choose a 
model of XML-literal-equality in RDF graphs which is based on syntax event 
equivalence rather than canonical XML equality.

#g


------------
Graham Klyne
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Received on Friday, 9 July 2004 06:36:05 UTC

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