# Quantities of arbitrary units in openEHR
**URL:** https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514
**Category:** Technical (archive)
**Created:** [24 January 2018 09:52 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514 "2018-01-24T09:52:31Z")
**Posts on this page:** 5
**Page:** 3
### Author:  [@system](https://discourse.openehr.org/u/system)
#### Post date: [29 January 2018 17:27 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514/41 "2018-01-29T17:27:25Z")
Yes, I understand the decision, but IO regard it as a quick decision which can cause problems on the longer term.
For the record, I object against this decision for the last time. (or else it will get boring ) đ
UCUM does not have an infrastructure for translations, so translations will be done "in the wild", this may be good or may be bad.
SNOMED has an infrastructure for professional translations, SNOMED also supports units and hierarchies, like UCUM-properties.
It is of course a matter of taste, and what a customer wants. But I think, OpenEHR should offer a customer optional facilities for professional translations of the units. Pinning the DvQuantity to UCUM in the RM makes it impossible for the customer to chose for a professional translation on archetype-level.
There is another disadvantage of this unnecessary inseparability of the RM and UCUM, it is against the OpenEHR philosophy to offer as much freedom in modeling as possible.
So take your decisions wisely đ
Best regards
Bert
---
### Author:  [@siljelb](https://discourse.openehr.org/u/siljelb)
#### Post date: [30 January 2018 14:55 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514/42 "2018-01-30T14:55:53Z")
Hi Pablo,
This is our current modelling, for reference (the administration unit denominator isnât modelled):
I donât see how either ordinals or proportions, the way they currently work, can be of any help here.
Regards,
**Silje**
---
### Author:  [@system](https://discourse.openehr.org/u/system)
#### Post date: [30 January 2018 16:24 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514/43 "2018-01-30T16:24:22Z")
Hi Silje,
My thinking is for your use case, DV\_QUANTITY doesnât apply for arbitrary, since those seem not related with physical properties (mass, length, area, concentration, etc.)
As I said, âlevel of Xâ makes me think of DV\_ORDINAL.
DV\_PROPORTION would be used for numerator / denominator modeling, but currently doesnât support units so itâs real / real. My suggestion was to analyze the change from that to an arbitrary type for each numerator and denominator, so you can model DV\_QUANTITY / DV\_QUANTITY proportions.
Also DV\_ORDINAL doesnât have a unit but has a DV\_CODED\_TEXT, maybe your arbitrary units are really terms from a given terminology, so this might be good to model that.
But as I said, for this specific use case you might need to use many data points (ELEMENTS) of different types, inside a CLUSTER to be able to comply with all your requirements (please check my previous message where I outlined your requirements as I understood them).
Hope that helps.
> **(attachments)**
>
> 
---
### Author:  [@system](https://discourse.openehr.org/u/system)
#### Post date: [30 January 2018 16:30 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514/44 "2018-01-30T16:30:37Z")
or even DV\_COUNT.
I have asked some questions of knowledgeable ontology sources; will post any replies I get here.
- thomas
---
### Author:  [@system](https://discourse.openehr.org/u/system)
#### Post date: [30 January 2018 16:44 UTC](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514/45 "2018-01-30T16:44:09Z")
But you canât specify terms in DV\_COUNT while DV\_ORDINAL.symbol can be used to specify the arbitrary units but not as physical property units of measure, but as a terminology concept / term.
[Previous page](https://discourse.openehr.org/t/quantities-of-arbitrary-units-in-openehr/15514.md?page=2)