- From: Dave Beckett <dave.beckett@bristol.ac.uk>
- Date: Fri, 15 Feb 2002 13:59:22 +0000
- To: Patrick Stickler <patrick.stickler@nokia.com>
- cc: Brian McBride <bwm@hplb.hpl.hp.com>, RDF Core <w3c-rdfcore-wg@w3.org>
>>>Patrick Stickler said: > On 2002-02-15 12:10, "ext Brian McBride" <bwm@hplb.hpl.hp.com> wrote: > > > At 11:04 15/02/2002 +0200, Patrick Stickler wrote: > > [...] > >> <dc:date rdf:value="2002-02-14" rdf:dtype="&xsd;date"/> > > > > Am I right that under the current proposal this can be more > > compactly written: > > > > <dc:date xsd:date="2002-02-14"/> > > Yes and no. It is more compact, but is less local (thus it > is not exactly an equivalent variant of the doublet idiom). > > In this case, it is not clear from the RDF that xsd:date is a > datatype. It could be any kind of property at all. It has > no more datatyping clarity to the parser than > > <dc:date foo:bar="2002-02-14"/> Yeah, that is an issue, but maybe just one of education - choose clearly the prefixes and local names for data type URIs. If the foo:bar property isn't given an RDF datatype meaning via some extra info, then it remains a property? > And it is unclear, if e.g xml:lang is specified, whether > the value of xsd:date or foo:bar is the actual literal > value of the dc:date property or just some extra attribution > of the bNode. Thus, schema knowledge would be required > by the parser (not just pre-defined automatic statements > in the spec) to know for sure that xsd:date or foo:bar > should be treated as rdf:value. > > And one would not, I think, expect xml:lang to apply to > all attributes of the element -- or really to any of > the attributes, but rather only the content of the element, > and it's just a trick of rdf:value that the content can > be hidden (contracted) into an attribute. "A special attribute named xml:lang may be inserted in documents to specify the language used in the contents and attribute values of any element in an XML document. " -- http://www.w3.org/TR/2000/REC-xml-20001006#sec-lang-tag so it is clear that xml:lang affects attribute values. > If I have > > <dc:title rdf:value="Foo" xml:lang="en" x:scope="237a87"/> > > we're saying that "Foo" is English, but not "237a87". XML says both are. > Yet if I have > > <dc:title xsd:string="Foo" xml:lang="en" x:scope="237a87"/> > > how does the parser know which attribute, if any, denotes > the actual content of the dc:title property element? 'actual content'? XML says attribute starting with 'xml' are reserved; so that leaves two for the XML-application, RDF here, to use. The triple mapping that RDF/XML provides to ntriples is quite clear, it gives you: _:x dc:title _:y . _:y xsd:string "Foo"(en) . _:y x:scope "237a87"(en) . What 'actual content' do you mean? Some RDF application may understand that xsd:string rdf:subPropertyOf rdf:value and then do the datatyping thing, or not. > Thus, with the datatype triple idiom, the parser cannot > know what is or is not the content of the property element > to which xml:lang is to be attached simply from the > vocabulary used in the idiom itself. > > I admit that it's a handy form of expression, but these > issues have to be resolved before we're completely > done, I think. I don't see any issues. <snip/> > Though, as pointed out above, proper attachment of xml:lang > to the literal either requires schema knowledge or results > in over-attachment to all attributes. No. I can't see any implementation problems with the above. Dave
Received on Friday, 15 February 2002 09:02:35 UTC