# DV_QUANTITY or DV_DURATION?

**Category:** [Technical (archive)](https://discourse.openehr.org/c/technical-archive/156)
**Created:** 2010-12-17 13:22 UTC
**Views:** 3
**Replies:** 3
**URL:** https://discourse.openehr.org/t/dv-quantity-or-dv-duration/15035

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## Post #1 by @Leonardo_Moretti

I'm wondering which is the correct use of DV\_DURATION and DV\_QUANTITY\.\.\.
When using DV\_QUANTITY with property attribute 'time' \(openehr::128\) and
when using DV\_DURATION?

Regards
leo

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## Post #2 by @thomas.beale

The most usual uses are:

- DV_DURATION - time periods in the 'social' timescale, e.g. hours, days, weeks, months, years - e.g. pregnancy, Expected Date of Delivery, duration of migraine

- DV_QUANTITY - short time periods, being treated more mathematically, e.g. seconds or smaller, minutes and hours
both can be used for computation and can be inter-converted.

- thomas

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## Post #3 by @ian.mcnicoll

Hi Thomas,

I think I have used DV\+DURATION in all of these circumstances\.\. My
impression has been that DV\_QUANTITY with time property was
deprecated\.

Ian

Dr Ian McNicoll
office / fax  \+44\(0\)1536 414994
mobile \+44 \(0\)775 209 7859
skype ianmcnicoll
ian\.mcnicoll@oceaninformatics\.com

Clinical analyst, Ocean Informatics
openEHR Clinical Knowledge Editor www\.openehr\.org/knowledge
Honorary Senior Research Associate, CHIME, UCL
BCS Primary Health Care SG Group www\.phcsg\.org

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## Post #4 by @system

Hi

The advantage of duration is that time can be expressed in the usual way 2
months, 6 weeks, 2hr 30min, 5min 30sec etc\.

The Quantity has the advantage of being able to set a fixed unit\. This is
necessary sometimes and although this can be done with duration it is not
really the focus\. I think both have a role\.

Cheers, Sam

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**Canonical:** https://discourse.openehr.org/t/dv-quantity-or-dv-duration/15035
**Original content:** https://discourse.openehr.org/t/dv-quantity-or-dv-duration/15035