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Re: How to use notations from classification schemes in SKOS

From: Alistair Miles <a.j.miles@rl.ac.uk>
Date: Mon, 13 Feb 2006 15:19:09 +0000
Message-ID: <43F0A36D.400@rl.ac.uk>
To: "Svensson, Lars" <svensson@dbf.ddb.de>
CC: public-esw-thes@w3.org

Hi Lars,

The very early 'Thesaurus Interchange Format' on which SKOS is based had 
a property called 'classificationCode' which was intended for notations.

SKOS Core used to have a very badly named property called 
'skos:externalID' which was intended to provide a non-URI identifier for 
a concept ('external' as in 'outside the web' - that was my bad idea, 
apologies - see section 3.4 in [1]). It replaced the 
'classificationCode' property. In the 2004 SWAD-Europe report 'RDF 
Encoding of Classification Schemes' [4] I used a sub-property of 
skos:externalID to represent a PACS classification code.

Later in 2004 I made a proposal to replace the 'skos:externalID' 
property with something call 'skos:localID' - see [2]. The idea was that 
the value of a 'localID' is a literal that identifies a concept uniquely 
within the scope of a thesaurus or classification scheme. We ultimately 
decided that the dc:identifier property could be used for this purpose 
(see [3]) and decided to deprecated skos:externalID and replace it with 
dc:identifier. The idea was that each thesaurus or classification scheme 
could create a sub-property of dc:identifier to capture their own 
notations, although we never added anything to the SKOS Core Guide to 
indicate how to do this.

However, I have been thinking for a while that a SKOS 'notation' 
property would be a good idea after all. Such a property would have a 
meaning that goes beyond dc:identifier, but is common to all 
classification schemes and thesauri.

I would be happy to support a proposal for a 'skos:notation' property. I 
would suggest that the property had the following meanings:

  - The main purpose of the property is to provide a human-friendly 
identifier for the concept, whose value is not a recognisable word or 
collocation of words from any natural language.

  - The value of the property should be a literal that uniquely 
identifies the concept within the scope of a given thesaurus or 
classification scheme.

  - The value should be a typed literal, where the datatype defines both 
the scope of reference, and the lexical space of allowed values.

So e.g. the classification scheme with URI <http://example.com/myScheme> 
defines a datatype for notations and allocates the URI 
<http://example.com/myScheme/Notation> to this datatype. It then uses 
the skos:notation property as in:

ex:concept01 a skos:Concept;
   skos:prefLabel 'love'@en;
   skos:altLabel 'affection'@en;
   skos:notation '10.024.354'^^<http://example.com/myScheme/Notation>.



[1] http://www.w3.org/2001/sw/Europe/reports/thes/1.0/guide/20040504/
[2] http://lists.w3.org/Archives/Public/public-esw-thes/2004Aug/0064.html
[3] http://lists.w3.org/Archives/Public/public-esw-thes/2004Sep/0002.html
[4] http://www.w3.org/2001/sw/Europe/reports/thes/8.5/

Svensson, Lars wrote:
> [This question has been on the list before [1][2], but I found no
> ultimate answer and thus feel free to post again. Sorry for any
> inconvenience!]
> Classification schemes like the Universal Decimal Classification, MCS,
> or PACS usually have two human-readable labels: One containing a
> notation (usually a combination of digits and letters following a
> specific syntax, so that it's possible to see super-/subclass
> relationships and ideally to identify precoordinated notations), the
> other one being kind of free-format text only. Both labels are intended
> for human use. For the second one, I would probably use skos:prefLabel,
> but is there a specific label for use with notations? I wouldn't be
> comfortable to use skos:altLabel, since the semantic is quite different,
> but I can't find a skos:notation property or anything similar. Have I
> missed anything?
> Thanks
> Lars
> [1] http://lists.w3.org/Archives/Public/public-esw-thes/2005Jan/0075 
> [2] http://lists.w3.org/Archives/Public/public-esw-thes/2005Feb/0033

Alistair Miles
Research Associate
CCLRC - Rutherford Appleton Laboratory
Building R1 Room 1.60
Fermi Avenue
Oxfordshire OX11 0QX
United Kingdom
Email: a.j.miles@rl.ac.uk
Tel: +44 (0)1235 445440
Received on Monday, 13 February 2006 15:19:27 UTC

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