W3C home > Mailing lists > Public > public-lod@w3.org > November 2010

Re: isDefinedBy and isDescribedBy, Tale of two missing predicates

From: Toby Inkster <tai@g5n.co.uk>
Date: Mon, 8 Nov 2010 11:17:32 +0000
To: Ian Davis <lists@iandavis.com>
Cc: nathan@webr3.org, Leigh Dodds <leigh.dodds@talis.com>, Dave Reynolds <dave.e.reynolds@gmail.com>, "public-lod@w3.org" <public-lod@w3.org>
Message-ID: <20101108111732.1c2bb15c@miranda.g5n.co.uk>
On Fri, 5 Nov 2010 15:53:34 +0000
Ian Davis <lists@iandavis.com> wrote:

> Suppose I assign the ID 'mars' to represent the planet mars in my RDFa
> document. I can then refer to it using http://example.com/foo#mars.
> What does it mean when my javascript calls
> document.getElementById('mars')? Should I expect now to manipulate the
> planet mars?

If you are using the URI <http://example.com/foo#mars> to represent a
planet, then you should not use the same URI to represent an HTML
element, as it's likely that the set of HTML elements and the set of
planets are disjoint. (In Aug 2006 the IAU finally settled on a
definition of planets that at least seems to exclude HTML elements from
being planets in their own right.)

Given that the planet Mars and your HTML element are in disjoint sets,
they must be separate entities so must not share a URI.

The upshot of this, is that if you use the following RDFa:

	<div about="#mars" typeof="iau:Planet">

then you ought not to be including id="mars" on any element in your
document, as it introduces ambiguity over what is identified by the
URI <http://example.com/foo#mars>. 

Take a look at my Ontology at <http://ontologi.es/persona> which is
serialised in RDFa. It uses a URI of:


to identify a class, and:


to identify an element in the document where a description of the
class can be found.

Toby A Inkster
Received on Monday, 8 November 2010 11:18:12 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 7 January 2015 15:16:10 UTC