RE: Completing the W3C work on quantities, units and scales

Hi David,

Just small comments:
- still don't like the name "quantities of the same kind". If really
neccesary in the final ontology (your latest countercomments suggest
maybe not) I would call it something like QuantityType or QuantitySpace.
- the conceptual order of things seem: quantity, scale, unit (unit when
poss.)
(ie we also have a scale:metre (even in our diagrams we have scale and
not unit...))
So maybe better always present in this way?

For the rest all ok!
And many thanks for your very clear countercomments at the wiki!

Cheers Michel 

At note 5: I still think we need owl:ObjectProperty on base level and
connect waterLineLength ...


-----Original Message-----
From: public-xg-w3pm-request@w3.org
[mailto:public-xg-w3pm-request@w3.org] On Behalf Of David Leal
Sent: 14 July 2008 13:27
To: public-xg-w3pm@w3.org
Subject: 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

------------------------------------------------------------------------
----
---------------

Completing the W3C work on quantities, units and scales
-------------------------------------------------------

Responsible organisations
-------------------------
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
----------
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/Thermodynamic
Temp
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
============================================================


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Received on Monday, 14 July 2008 12:06:10 UTC