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[Proposal] SKOS-Core Schema Management and Evolution

From: Miles, AJ (Alistair) <A.J.Miles@rl.ac.uk>
Date: Mon, 26 Jul 2004 16:40:59 +0100
Message-ID: <350DC7048372D31197F200902773DF4C05E50B44@exchange11.rl.ac.uk>
To: "'public-esw-thes@w3.org'" <public-esw-thes@w3.org>

To cope with evolution and change of the SKOS-Core RDF schema over both the
current development iteration and the longer term, I propose the following:

[N.B. these proposals are a copy of the
http://esw.w3.org/topic/SkosDev_2fSchemaManagement wiki page as it stood at
the time of writing].


1: Namespace Management

Currently the SKOS-Core RDF schema resides under the namespace
<http://www.w3.org/2004/02/skos/core#>. 

It is proposed that there be no short or medium term versioning of this
schema using different namespaces ... i.e. the terms of the schema will be
maintained under the current namespace for the forseeable future. 


2: Term Status Management

To manage the status of SKOS-Core RDF schema it is proposed that the Vocab
Status RDF schema <http://www.w3.org/2003/06/sw-vocab-status/ns#> is used.
... This involves assigning every SKOS class and property a 'term_status'
value, which is formally expressed as part of the schema. 

For example ... 

        <rdfs:Class rdf:ID="ConceptScheme"> 
                <rdfs:label>Concept Scheme</rdfs:label> 
                <rdfs:comment>A concept scheme is a collection of
concepts.</rdfs:comment> 
                <ts:term_status>stable</ts:term_status> 
        </rdfs:Class> 

The 'term_status' property may take one of three values: 'unstable'
'testing' or 'stable'. 

These values correspond to the 'alpha' 'beta' and 'stable' values given to
software releases. However, it is not entirely clear what these values
should imply for RDF schema terms. 

I suggest the following definitions, as a starting point ... to be clarified
and refined: 

unstable ... this term has been newly added, and no testing has been carried
out. Implementations using this term should realise that its meaning may be
expected to change, or it may be removed at any time. 

testing ... this term is currently undergoing testing and evaluation. This
means that it will probably persist, although its exact meaning may change. 

stable ... this term is stable and has been subjected to testing and
evaluation. Implementers can expect this term to persist, and for its
meaning to remain unchanged. 

All status changes within SKOS RDF schemas will be reported on the SKOS
change log <http://esw.w3.org/mt/esw/archives/cat_skos_changelog.html>. 


3: Deprecation and Replacement of Terms

To manage the deprecation and replacement of terms within the schema, I
propose the use of the owl:DeprecatedClass and owl:DeprecatedProperty
classes. ... the owl:versionInfo property is then used to indicate what
class or property should now be used instead. 

For example ... 

        <owl:DeprecatedClass rdf:ID="TopConcept"> 
                <rdfs:label>Top Concept</rdfs:label> 
                <rdfs:comment>A concept that sits at the top of the concept
hierarchy.</rdfs:comment> 
                <owl:versionInfo>This class is now deprecated.  To indicate
the top concepts for a particular scheme, use the new skos:hasTopConcept
property instead.</owl:versionInfo> 
        </owl:DeprecatedClass> 


Yours,

Alistair.

---
Alistair Miles
Research Associate
CCLRC - Rutherford Appleton Laboratory
Building R1 Room 1.60
Fermi Avenue
Chilton
Didcot
Oxfordshire OX11 0QX
United Kingdom
Email:        a.j.miles@rl.ac.uk
Tel: +44 (0)1235 445440
Received on Monday, 26 July 2004 11:42:11 GMT

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