DIWG Requests Guidance on Ontologies for Units

Hello Guus,

One of the areas of interest of the Device Independence Working Group relates to the physical characteristics of devices used to access web sites. In trying to specify these characteristics we find that we have a need to define the physical units in which they may be represented. For consistency with other W3C specifications, such as CSS, we need to represent a reasonably wide range of units. For example, in length measurements we need to represent inches, centimeters, picas, points and so on.

We view the information we are trying to represent as metadata, and hence we are using RDF as the underlying technology. In addition, we would like to be able to represent the units associated with these characteristics as URIs. 

At the risk of exposing to public scrutiny just what an RDF neophyte I am, I believe we'd like to be able to construct statements such as:

  <dc:UsableDisplayWidth rdf:ID="cpcUW">
      <dc:lengthValue rdf:datatype="&xs;decimal">0.152</dc:lengthValue>
      <dc:lengthUnit rdf:resource="http://sweet.jpl.nasa.gov/ontology/units.owl#meter"/>
  </dc:UsableDisplayWidth>

In this example, UsableDisplayWidth is a class for the particular characteristic, lengthValue the value of the length and lengthUnit the physical units associated with lengthValue. The particular rdf:resource value is the definition of meter in the SWEET units ontology. &xs; is an entity containing the base URI of the XML schema datatypes.

On the assumption that this approach is appropriate, we are interested in finding existing Ontologies that we could reference using URIs and that would provide identification for additional units.

Stuart Williams from the TAG pointed us to the SWEET ontologies, but suggested that we contact SWBP-WG to see if you had any additional recommendations. 

Any guidance you could give on associating units with values or or pointers to appropriate ontologies would be very much appreciated.

Best wishes 
Rhys Lewis, Chair DIWG

Received on Friday, 2 July 2004 05:43:12 UTC