# Are DV_TIME_SPECIFICATION classes used on implementations or supported by modeling tools?

**Category:** [Specifications](https://discourse.openehr.org/c/specifications/6)
**Created:** 2022-05-21 04:43 UTC
**Views:** 408
**Replies:** 1
**URL:** https://discourse.openehr.org/t/are-dv-time-specification-classes-used-on-implementations-or-supported-by-modeling-tools/2640

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## Post #1 by @pablo

For the conformance data validation test cases I have some test cases pending for DV_GENERAL_TIME_SPECIFICATION and DV_PERIODIC_TIME_SPECIFICATION classes from https://specifications.openehr.org/releases/RM/Release-1.1.0/data_types.html#_time_specification_package

But I'm not sure if those classes are really used or not (like DV_PARAGRAPH) in the real world. So I don't want to create test cases for something nobody implements.

Thanks!

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## Post #2 by @thomas.beale

As far as I know, no-one uses them, and they would be a candidate for replacement if we can prove this. However, we need to describe in the specs what they are replaced with.

EDIT: let me add a bit to that. The primary requirement being met by these classes was intended to be the ability to state a future time 'formula' for e.g. prescription medication, i.e. things like 3 times a day with meals.

The GTS approach was to do it syntactically. Today, it is done with an archetyped data structure (currently [CLUSTER.therapeutic_direction](https://ckm.openehr.org/ckm/archetypes/1013.1.2753/mindmap)), so it's not even in the reference model. There is also a field in INSTRUCTION.medication_order called Parsable directions, which is used to pick up 'legacy' medical syntax like '3td po' (3 times/day per oral).

However, the need to express future times also exists in Task Planning, and having a Foundation type that could do the job would be useful. At the moment there is [`TIME_SPECIFIER`](https://specifications.openehr.org/releases/PROC/latest/task_planning.html#_task_planning_model_overview).

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**Canonical:** https://discourse.openehr.org/t/are-dv-time-specification-classes-used-on-implementations-or-supported-by-modeling-tools/2640
**Original content:** https://discourse.openehr.org/t/are-dv-time-specification-classes-used-on-implementations-or-supported-by-modeling-tools/2640