Completing the W3C work on quantities, units and scales

Dear All,

All that we do on quantities, units and scales relies upon the metrology
standards issued by BIPM, ISO and IEC. These organisations have to allocate
URIs before anything we do can work.

We need to make a concrete proposal to BIPM, ISO and IEC in order to ensure
that this happens. A draft of sucha a proposal is attached. What do people
think?

Best regards,
David

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Completing the W3C work on quantities, units and scales
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Responsible organisations
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The W3C Product modelling XG can make proposals about the use of quantities,
units and scales on the Web, but these proposals can only become reality if
the organisations responsible for defining quantities, units and scales
assign URIs to them.

NOTE Before the Web, the responsible organisations would define the objects
and their names. These names could be regarded as keywords, and their use
within data structures could be specified.

Using Web technologies, an object requires a URI. The URI should be assigned
by the organisation that defines the object for the following reasons:
1) The namespace of the URI indicates the organisation, and hence the level
of trust which can be placed in the definition of the object.
2) The organisation that defines the object can control what is obtained by
dereferencing the URI. This could be the definition of the object. This also
could be a statement that use of the object is now deprecated, and a
recommendation of a successor object.
3) If assigning the URI is left to other organisations, then it may be done
more than once.

A Proposal
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The W3C Product Modelling XG requests BIPM, ISO, IEC or a combination of
these organisations to allocate URIs to:
- sets of quantities of the same kind. e.g. length, thermodynamic temperature;
- units, e.g. metre, second, Ampere, Kelvin;
- scales, e.g. Celsius

NOTE Probably the W3C community would prefer HTTP URIs. This would allow
dereferencing using HTTP if the responsible organisations chose to provide
representations for the URIs. However, URNs would also be adequate.

Use of the URIs
---------------
The use of the URIs to record scientific or product data requires additional
standards. These standards could be created by W3C or by technical
committees within ISO or IEC concerned with data representation rather than
quantities, units and scales.

Example
-------
Assume that:
- BIPM allocates:
  - metre   - http://www.bipm.org/si/metre
  - Celsius - http://www.bipm.org/si/celsius

- ISO and IEC allocates:
  - length  - http://www.iso.org/std/iso-iec/80000/-1/tech/Length
  - thermodynamic temperature
            -
http://www.iso.org/std/iso-iec/80000/-1/tech/ThermodynamicTemperature

- W3C allocates:
  - the reals
            - http://www.w3.org/TR/MathML2/chapter4.html#contm.reals

NOTE 1 The ISO-IEC example is based upon the proposal for an ISO URN [RFC
5141 - http://tools.ietf.org/html/draft-goodwin-iso-urn-03] , but adapted to
be an HTTP URI.

NOTE 2 A URI for the field of real numbers (see
http://mathworld.wolfram.com/RealNumber.html) is required. For this example,
a URI from MathML is used.

These URIs could be used by other organisations or technical committees to
make statements such as:

 <owl:Thing rdf:about="http://www.bipm.org/si/metre">
  <rdf:type rdf:resource="http://www.iso.org/std/iso-iec/80000/-1/tech/Length"/>
 </owl:Thing>
 
 <owl:FunctionalProperty rdf:about="http://www.bipm.org/si/celsius">
  <rdfs:domain
rdf:resource="http://www.iso.org/std/iso-iec/80000/-1/tech/ThermodynamicTemp
erature"/>
  <rdfs:range
rdf:resource="http://www.w3.org/TR/MathML2/chapter4.html#contm.reals"/>
 </owl:FunctionalProperty>

The organisations which control the URIs may be unwilling to make these
statements, because they rely upon the precise meaning of owl:Thing,
rdf:type, owl:FunctionalProperty, rdfs:domain and rdfs:range. Experts in
metrology are not necessarily experts in information representation, and may
not want to take responsibility for this.

Hence these statements could be published by W3C. The set of statements
would be allocated a W3C URI to make it clear who is responsible for them.

============================================================
David Leal
CAESAR Systems Limited
29 Somertrees Avenue
Lee London SE12 0BS
tel:      +44 (0)20 8857 1095
mob:      +44 (0)77 0702 6926
e-mail:   david.leal@caesarsystems.co.uk
web site: http://www.caesarsystems.co.uk
============================================================

Received on Monday, 14 July 2008 11:27:54 UTC