UCUM/SNOMED/custom units

Technical (archive)
1

I wonder if it is possible to use other units then UCUM units in DV_QUANTITY. I read from Pablo in Stackoverflow that the SEC is considering custom units. I think this is great, but I see some problems coming up. I have some questions about this,

I wonder how you can do that without changing the DV_QUANTITY-definition, because it has a units-attribute, it says it must be expressed in UCUM syntax. It does not say anything about the unit itself, only about the notation.

Must we understand UCUM so, that it has not only a syntax for its own units, but also for custom units?

That is strange, because custom-units (non-UCUM) can carry custom (non-UCUM) syntax-descriptions. So if we are writing a custom unit, and using a syntax to specify it, then we need two references, don't we?

One reference for where the unit comes from, and one reference for the syntax?

A custom unit can also occur in another standard, for example SNOMED, also a UCUM-unit can occur in SNOMED, but is it sure it means the same? Normally we are very prudent about things like this.
I found a HL7 wiki about this. Someone did some thinking about this. I think that also applies to OpenEhr.

http://wiki.hl7.org/index.php?title=Representation_of_Units

Best regards
Bert Verhees

2

Units need to be (and will be) revamped, we also need other things already discussed in other posts like rubric, long descriptions (which could be language dependent), etc. This could be very useful for better describing custom UCUM units too.

Several alternatives are being explored in order to not break current units definitions. Maybe adding an optional codephrase or terminology mapping could do the trick, as then you can tell where the unit comes from and allows you to provide a “code” which could either contain a Snomed code or a UCUM expression. Inputs are appreciated as always :slight_smile:

Regards

3

I think your suggested solution is just right :wink:
But possible I do not oversee all consequences

Bert

4

REF https://openehr.atlassian.net/browse/SPECPR-96