- From: Misha Wolf <Misha.Wolf@reuters.com>
- Date: Tue, 27 Jun 2006 15:06:36 +0100
- To: public-rdf-in-xhtml-tf@w3.org, semantic-web@w3.org, www-tag@w3.org
[Updated in the light of the recent mails from Ivan, Dan and Shane] This survey (see 7a-7h) has evolved from [3]. The data points presented reflect my incomplete understanding. Please help by correcting the ones that are wrong and providing the missing (or additional) data points. The character "~" has been used below to mean "approximately". For context, see: [1] RDFa Primer 1.0, 16 May 2006 http://www.w3.org/TR/2006/WD-xhtml-rdfa-primer-20060516/ [2] News Taxonomies presentation to the W3C AC, given on 22 May 2006 http://lists.w3.org/Archives/Public/www-archive/2006Jun/0013.html [3] CURIEs: A proposal, 2 June 2006 http://lists.w3.org/Archives/Public/www-tag/2006Jun/0007.html 1 We agree on a generic syntax and generic rules for Compact URIs (CURIEs). 2 We agree that restricted syntaxes and rules will be (or have been) defined for specific purposes. One such purpose is XML Namespaces and QNames. 3 Groups within the W3C and elsewhere will define other restricted syntaxes and rules for their own purposes. 4 The generic syntax for a CURIE in an attribute value will be: <foo bar="prefix:suffix"/> 5 The generic syntax for multiple CURIEs in an attribute value will (where permitted) be: <foo bar="prefix1:suffix1 ... prefixN:suffixN"/> 6 Both the prefix and the suffix may (in the generic case) be numeric. 7 Each language must specify: 7a the syntactic constraints (if any) on the prefix and suffix. XMLNS : prefix = NCNAME (can be omitted); suffix = NCNAME XHTML : prefix = NCNAME (can be omitted); suffix = IRI NewsML 2 : prefix = NCNameChar+ ; suffix = NCNameChar+ RDF/XML : Not applicable N3 : prefix = NCNAME (~) ; suffix = NCNAME (~) The lexical details of N3 are a work in progress; the grammar that TimBL maintains says... qname (([a-zA-Z_][a-zA-Z0-9_]*)?:)?[a-zA-Z_][a-zA-Z0-9_]* http://www.w3.org/2000/10/swap/grammar/n3-report.html but [Dan thinks] the code and tests differ. We seem to have a test for a non-ascii character in a name, but [Dan] can't find it in the log of the tests run for the latest release, so [he's] not sure what it's status is. Turtle : prefix = NCNAME (~) ; suffix = NCNAME (~) turtle seems to disallow "." in names altogether. And [Dan doesn't] see "_" there either: http://www.dajobe.org/2004/01/turtle/#nameChar SPARQL : prefix = NCNAME (~) ; suffix = NCNAME (~) In SPARQL, names of the form _:xyz are used for something other than URI abbreviations. The grammar seems to prohibit prefixes from starting with "_". And in both the prefix and the suffix, starting with a "." seems to be prohibited. For details, see http://www.w3.org/TR/rdf-sparql-query/#rNCNAME_PREFIX 7b how CURIEs and URIs are distinguished, eg through dedicated attributes or through a special syntax. XMLNS : Not applicable XHTML : Mix of dedicated attributes and special syntax ("[a:b]") for non-dedicated attributes NewsML 2 : Dedicated attributes RDF/XML : Not applicable N3 : In SPARQL, N3, and turtle, URI references are written <thusly>, and qnames can't have <>s in them Turtle : See above SPARQL : See above 7c the mechanism for specifying the prefix-to-IRI mapping. The mechanism may use information provided out-of-band. XMLNS : xmlns attribute XHTML : xmlns attribute NewsML 2 : <scheme alias="enwiki" uri="http://en.wikipedia.org/wiki/" /> RDF/XML : xmlns attribute N3 : @prefix abc: <http://example/abc#>. Turtle : @prefix abc: <http://example/abc#>. SPARQL : PREFIX abc: <http://example/abc#> 7d whether and, if so, how the prefix and suffix are combined to form an IRI. XMLNS : Left to each language to specify XHTML : Plain concatenation, including cases such as: prefixIRI = http://www.example.com/partial_ suffix = folder/item fullIRI = http://www.example.com/partial_folder/item NewsML 2 : For vocabularies managed by the IPTC, we're considering: <vocabIRI> & "#_" & <code> or plain concatenation, coupled with vocabIRIs ending with "?" or "/" or "#_" For vocabularies not managed by the IPTC: Left to each vocabulary authority to specify RDF/XML : Plain concatenation N3 : Plain concatenation Turtle : Plain concatenation SPARQL : Plain concatenation 7e whether the prefix and suffix form a tuple (other than purely syntactically) and/or whether they are a compact representation for an IRI. XMLNS : Tuple only XHTML : Compact representation for an IRI only NewsML 2 : Tuple and compact representation for an IRI RDF/XML : In RDF/XML, the tuple from XMLNS is used as an IRI abbreviation. There are lots of cases where it's useful to round-trip back to the tuple, though that's never strictly required. N3 : See above Turtle : See above SPARQL : See above 7f whether the dereferencing of the IRI mapped to the prefix is required to yield a useful and relevant information resource. XMLNS : Not required, but the Architecture of the WWW states: "The owner of an XML namespace name SHOULD make available material intended for people to read and material optimized for software agents in order to meet the needs of those who will use the namespace vocabulary." XHTML : Not required; note that the prefix may correspond to a partial, nonsensical IRI, without the suffix (see 7d) NewsML 2 : Required RDF/XML : The URI mapped to the prefix isn't relevant at the RDF abstract syntax level. It's handy to be able to look it up for RDF/XML consumers that only know they're looking at XML. N3 : See above Turtle : See above SPARQL : See above 7g whether the dereferencing of the IRI built from the prefix and suffix (and, possibly, also other building blocks) is required to yield a useful and relevant information resource. XMLNS : Left to each language to specify XHTML : The role attribute specification requires that roles be defined using RDF, and that the role QName (or CURIE) dereference to that definition. NewsML 2 : For vocabularies managed by the IPTC: MUST For vocabularies not managed by the IPTC: SHOULD RDF/XML : Is best practice N3 : See above Turtle : See above SPARQL : See above 7h whether any fragment identifiers in these IRIs are required to be legal XML names. XMLNS : Outside the scope of the spec XHTML : Outside the scope of the spec NewsML 2 : Yes RDF/XML : Outside the scope of the spec N3 : See above Turtle : See above SPARQL : See above 8 To avoid confusion with XML Namespaces and QNames: 8a The xmlns attribute is reserved for use with XML Namespaces and QNames. 8b If a prefix matches an xmlns declaration then the CURIE MUST be interpreted as a QName. Misha ------------------- NewsML 2 resources ------------------------------ http://www.iptc.org | http://www.iptc.org/std-dev/NAR/1.0 http://www.iptc.org/std-dev | http://groups.yahoo.com/group/newsml-2 To find out more about Reuters visit www.about.reuters.com Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Reuters Ltd.
Received on Tuesday, 27 June 2006 14:07:24 UTC