The arbitrary units are something different, but why does that matter at the data type level? If you understand the unit, you can work with it, if you don't you can't. Separating them because of ... Ontological ... Purity: just creates make -work for all the users who otherwise don't differentiate them
Grahame > On 18 May 2016, at 9:41 PM, Thomas Beale <[email protected]> wrote: > > >> On 18/05/2016 12:21, Grahame Grieve wrote: >> The main problem is that ucum units are not human readable units, > > right - my idea 13 years ago was to use the UCUM string as a key into > something that generated a human-readable form. For reasons that became > clearer since, I think we all agree that we need to embed not just the formal > form, but the human-readable form as well. So that's a fairly anodyne design > problem for the Quantity type in everyone's type system. I think we can solve > that in a reasonable way in openEHR. > >> and trying to force them to be will generate substantial pushback from end >> users. In USA, this is an open problem for CDA adoption. In Australia, I >> solved it by declaring that we would never retire valid ucum units in CDA. >> >> A secondary problem is discrete units like tablet, capsule etc which have no >> computable form in ucum > > I suspect this is the main problem for some people at least these days. > Scientifically speaking, anything like 'tablet', 'capsule', 'drop' etc isn't > a 'unit' in the science/physics sense; but in English (and most other > languages I suspect) we use the same word in a non-science sense to mean > 'discrete amount of anything', e.g. unit shares, 5mg tablet is the unit of > dosing, and so on. This makes people think the problem can be solved within > the model / language of scientific units. It can't in any clean way. > > So dose 'units' need to be understood as something different from scientific > units, and modelled in a different way. They are units of discretisation or > quantisation of material, not units of physical properties. > > - thomas > _______________________________________________ > openEHR-technical mailing list > [email protected] > http://lists.openehr.org/mailman/listinfo/openehr-technical_lists.openehr.org
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