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Hi Jonathan,

Presumably you are referring to the Units Ontology and not ontologies in
general? The Units Ontology appears to be mainly a controlled vocabulary
with no formal definition of relationships between units (and IMHO, in
need of some work, as e.g. " microgram per kilogram per day" is not
dimensionless).

An ontology can be used to define classes and properties to allow for
units conversion and to provide a mechanism for user defined units; I've
created such an ontology as proof-of-concept; next is Python code to map
RDF descriptions into CellML Canonical Unit Representations.

I agree 100% to only having a single way of specifying and defining
units. How about standard URIs backed by ReSTful web services that
return both RDF descriptions (from an ontology) and UnitsML (and for
that matter, [CellML, SBML, ...]) descriptions? Behind the scenes there
would a single "master" definition with mappings to different
representations. On the metadata side I envisage a reasoning system to
resolve "owl:sameAs" and similar equivalences. A web service could also
be used as a source of definitions for units checking and conversion
libraries.


Best regards,
Dave


On 28/09/11 10:41 PM, Jonathan Cooper wrote:
> Hi Bernard,
>
> I have thought about this a little. The biggest problem with using an
> ontology is that there doesn't seem to be any possibility of a
> mechanism for allowing user-defined units. The units ontology at
> present also doesn't appear to contain enough information to perform
> units conversions.
>
> It would certainly be beneficial to have a single units language
> across all COMBINE standards. Given that the SBML world has considered
> CellML's units to be too complicated, I'm not sure what they'd think
> of UnitsML! But producing our own version of such a standard does seem
> rather foolish. I wonder if there's scope for a 'lite' version of
> UnitsML that could be incorporated?
>
> From the very brief look I had, UnitsML does seem pretty
> comprehensive. I wasn't too enamoured of their approach to defining
> conversions though - you ought in most cases to be able to deduce
> appropriate conversions from the units definition, so it may be that
> they're lacking detail there.
>
> Best wishes,
> Jonathan
>
> On 28/09/11 10:34, Bernard de Bono wrote:
>> Hi,
>>
>> Is, alternatively, the use of an ontology for units also a
>> consideration? Terms from such an ontology could be applied to the
>> annotation of semantic metadata associated both with (i) model
>> variables, as well as (ii) related datasets.
>>
>> Thoughts most welcome.
>>
>> All the best,
>>
>> Bernard
>>
>>
>> On 28 September 2011 09:49, Steve McKeever
>> <Steve.McKeever at cs.ox.ac.uk <mailto:Steve.McKeever at cs.ox.ac.uk>>
>> wrote:
>>
>> Hi,
>> Only had a quick read through but it looks good, perhaps a bit
>> too comprehensive for CellML and FieldML. Hard to tell if it will
>> become *the* standard for units though.
>> Steve
>>
>> On 27 Sep 2011, at 01:04, David Brooks wrote:
>>
>>> Hi,
>>>
>>> I've come across the Units Markup Language (UnitsML,
>>> http://unitsml.nist.gov/), which is a project of the National
>>> Institute of Standards and Technology for encoding scientific
>>> units of measure in XML. It is currently being standardised by
>>> OASIS (the Working Draft is at
>>>
>>> http://www.oasis-open.org/committees/download.php/42538/UnitsML-Guide-v1.0-wd01.pdf).
>>>
>>> Should UnitsML be embedded in a future version of CellML? In
>>> FieldML? To become the preferred way to specify units in the
>>> various MLs??
>>>
>>>
>>> Regards,
>>> Dave
>>> _______________________________________________
>>> cellml-discussion mailing list
>>> cellml-discussion at cellml.org <mailto:cellml-discussion at
>>> cellml.org>
>>> http://lists.cellml.org/mailman/listinfo/cellml-discussion
>>
>>
>> _______________________________________________
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>>
>
>
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• [cellml-discussion] UnitsML, David Brooks, 09/27/2011
  • [cellml-discussion] UnitsML, Steve McKeever, 09/28/2011
    • [cellml-discussion] UnitsML, Bernard de Bono, 09/28/2011
      • [cellml-discussion] UnitsML, Jonathan Cooper, 09/28/2011
        • [cellml-discussion] UnitsML, David Brooks, 09/29/2011

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