- From: John Cowan <cowan@locke.ccil.org>
- Date: Wed, 22 Sep 1999 17:33:43 -0400 (EDT)
- To: swick@w3.org
- Cc: caro@adobe.com, rdf-dev@mailbase.ac.uk, www-rdf-comments@w3.org
Ralph R. Swick scripsit: > Good question. I agree with your assessment that the grammar as > specified does permit an empty element in the position of a property > expression and that this should generally not be encouraged. Since an empty element tag is the same as a start-tag followed immediately by the matching end-tag, it seems to me that a property like <xx:foo/> means the same as <xx:foo></xx:foo> which means that "" is the value of the xx:foo property; as you say, "" is a Literal like any other. If the empty string is sensible as an attribute value, it is also sensible as element content. > 3.If E is an empty element (no content), v is the resource whose > identifier is given by the resource attribute of E. If the > content of E contains no XML markup or if parseType="Literal" is > specified in the start tag of E then v is the content of E (a > literal). Otherwise, the content of E must be another Description > or container and v is the resource named by the (possibly > implicit) ID or about of that Description or container. > > omits the case that E is an empty element and E has no resource attribute. On my reading, it does *not* omit it; the content of E contains no XML markup, and is the empty string. > >triple('test#noValue', > > 'http://www.w3.org/RDF/Implementations/SiRPAC/', > > 'online#genid2'). > > > >But what is the value? Is it a made-up literal? A made-up resource? > > Janne seemed to have made the same guess that I proposed above; > the value is an anonymous resource, for which SiRPAC generates > an internal identifier. I think this result is a bug: the object of the triple should be simply ''. > I call this a SiRPAC bug. This clearly states that the value of > the test:noValue statement is the empty string (a Literal). > It is the same as > > <rdf:Description> > <test:noValue></test:noValue> > </rdf:Description> Which is equivalent to the empty tag "<test:noValue/>", per clause 3.1 of the XML Recommendation. -- John Cowan cowan@ccil.org I am a member of a civilization. --David Brin
Received on Wednesday, 22 September 1999 16:55:11 UTC