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Illustratation of prefix interaction details

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Mon, 25 Oct 2004 11:51:10 +0100
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
Message-Id: <20041025115110.69ca83b6@hoth.ilrt.bris.ac.uk>

Here's a pathological example of when prefixes and QNames can be confusing.

As I read the current grammar, this is legal.  Only
CONSTRUCT and DESCRIBE can use QName in the
  http://www.w3.org/TR/rdf-sparql-query/#prod-sparql-ReportFormat
between the two PrefixDecl allowed in the Query term.

Additionally FROM can also use QNames in 
  http://www.w3.org/TR/rdf-sparql-query/#prod-sparql-FromClause
since it indirectly uses 
  http://www.w3.org/TR/rdf-sparql-query/#prod-sparql-URI
which can be a QName.

So the a:bar are different URIs below.  (A DESCRIBE example would be similar)

The a:abc is a source URI or graph name.

Dave

------
PREFIX a: <http://example.org/ns1#>
PREFIX a: <http://example.org/ns2#>
CONSTRUCT
  (a:foo a:bar "blah")
PREFIX a: <http://example.org/ns3#>
FROM a:abc
WHERE
  (?x a:bar ?y)
Received on Monday, 25 October 2004 10:53:59 GMT

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