[SKOS] "SKOS RDF schema"

Dear all,

I'm looking at [1], also known as [2].

[1] http://www.w3.org/TR/2009/CR-skos-reference-20090317/skos.html
[2] http://www.w3.org/TR/2009/CR-skos-reference-20090317/skos

This document calls itself "SKOS Simple Knowledge
Organization System RDF Schema". 

One obvious problem is that the document is clearly an HTML
page and not an RDF schema. It may seem obvious to us that it
is really _about_ the RDF schema, but I can well imagine this
causing some confusion.

In the section of that document labeled "SKOS RDF Schema", then,
there is a link labeled "SKOS RDF Schema" which points to

[3] http://www.w3.org/2004/02/skos/core

which however -- since I am reading it in a browser --
content-negotiates back to [1]! 

However, the section does provide an additional link directly
to the schema itself ("download the RDF schema without content
negotiation") [4].

[4] http://www.w3.org/2004/02/skos/core.rdf

Given the title and introduction, then, the reader does not
necessarily expect to find the _contents_ of the RDF schema by
scrolling down one screen.

I find this all delightfully confusing... :-)

Some issues and suggestions for discussion:

-- Maybe call the Web document [1-2] "Contents of the RDF 
   schema for Simple Knowledge Organization System (SKOS)" 
   or "Expressing SKOS in RDF" - in effect, anything but
   "SKOS RDF schema" :-)

-- There should be a link labeled "SKOS RDF schema", but it 
   should link to [4] directly, not via content negotiation from
   [3].  The surrounding text, however, should describe the 
   content negotiation mechanism clearly.

-- Status of the document [1-2]: I'm not sure we have properly
   resolved this question. I think it would help the reader if
   this document describes itself as a readable ready-reference
   page which excerpts the contents of the RDF schema for SKOS,
   and that the RDF schema for SKOS is itself a formalisation
   of a subset of the semantic conditions described in SKOS
   Reference, and that the SKOS Reference has the status of W3C
   [Candidate] Recommendation.

   Like the OWL ontology [5], the RDF schema for SKOS does not
   assert any status for itself, though in the case of OWL,
   the contents of the schema are replicated in an appendix to
   the Recommendation document [6], arguably conferring on the
   schema itself a status of Recommendation, assuming it merely
   replicates the text in the appendix.

   [5] http://www.w3.org/2002/07/owl
   [6] http://www.w3.org/TR/owl-ref/#appB

   This text provides an opportunity to clarify that the SKOS
   Reference is the [Candidate] Recommendation and that [1],
   [2], and [4] are all excerpts of that Recommendation.
   (The text should point out that it is not possible to
   express all of the statements of the SKOS data model as RDF
   triples and thus the schema forms a "normative subset" of the
   specification.)

-- I'm wondering if this document [1-2] might be a good 
   place to introduce and link any DL versions of SKOS as per Sean's
   discussion in [7].  The document could briefly explain the need 
   to have a DL ontology in some contexts, describe the algorithm
   by which some of the axioms in [4] are "thrown away" (or filtered
   out).  In a way, the DL schema is arguably just another subset
   of the semantic conditions described SKOS Reference, albeit a 
   deliberately lossy one.  Grouping points to the RDF, HTML, and DL 
   excerpts together in one document would be helpful; and where else 
   to do that but in this document [1-2]?  (This assumes we want to 
   publish, or indeed say anything at all about, a DL version - also an
   issue for discussion.)

   [7] http://lists.w3.org/Archives/Public/public-swd-wg/2009Mar/0071.html

-- The HTML representation [1-2] should include labels.

-- If scripts were used to extract [1-2] from SKOS Reference and to 
   generate the DL version, it might be useful to point to those scripts
   or include them in an appendix.

-- Instead of replicating this construct separately for the XL namespace [8], 
   maybe SKOS and SKOS-XL could be usefully combined into one document
   "Expressions of SKOS Reference in RDF" (since SKOS Reference defines both
   the SKOS and XL namespaces).  Such a title would make clear that it 
   derives from SKOS Reference without implying that the document is itself
   an RDF schema.

   [8] http://www.w3.org/2006/07/SWD/SKOS/reference/20081001/skos-xl.html

If the document [1-2] were to do all of the above, might we
not want to formally approve it as a Working Group Note? That
would remove any confusion or ambiguity as to its status.  I 
hesitate because I'm not sure now under what circumstances a 
reader would normally click on or be redirected to this document
and whether, in those contexts, the reader might find it confusing
to encounter something with the status of Note.

Tom

-- 
Tom Baker <tbaker@tbaker.de>

Received on Monday, 6 April 2009 17:35:19 UTC