# How is the "constraint reference" used in "magnitude_status" within the "Dv_Quantity" in openEHR?

**Category:** [Clinical](https://discourse.openehr.org/c/clinical/5)
**Created:** 2023-08-09 14:49 UTC
**Views:** 359
**Replies:** 2
**URL:** https://discourse.openehr.org/t/how-is-the-constraint-reference-used-in-magnitude-status-within-the-dv-quantity-in-openehr/4329

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## Post #1 by @Zahra_Ghaempanah

hello everyone,
How is the "constraint reference" used in "magnitude_status" within the "Dv_Quantity" in openEHR? Could  everyone provide an example?
![image|690x335](upload://ioFeOOGnRooyAaQhc6nmllxAiNk.png)

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## Post #2 by @damoca

Since the possible values for that "magnitude_status" are just Strings of the mathematical symbols, it has little sense to use a constraint reference (acNNNN codes) in that attribute.

![image|690x176](upload://i8kyW11uLk5F0LFS8d9ooo0hseU.png)

It would be useful if it had been initially defined in the reference model as a terminological code, for example  a subset made of these SNOMED CT values:
![image|690x346](upload://r36tyy0vhB7oLM9EhFh5uRcI0nf.png)


https://browser.ihtsdotools.org/?perspective=full&conceptId1=276135000&edition=MAIN/2023-07-31&release=&languages=en

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## Post #3 by @thomas.beale

It would have been better if we had used a built-in enum I think, since that would have mapped to integers in most languages. Although we don't have a meta-type for constraining 'enums' as such... something to think about for next ADL version...

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**Canonical:** https://discourse.openehr.org/t/how-is-the-constraint-reference-used-in-magnitude-status-within-the-dv-quantity-in-openehr/4329
**Original content:** https://discourse.openehr.org/t/how-is-the-constraint-reference-used-in-magnitude-status-within-the-dv-quantity-in-openehr/4329