# Links between data elements in different archetypes

**Category:** [RM](https://discourse.openehr.org/c/rm/42)
**Created:** 2019-11-14 08:10 UTC
**Views:** 707
**Replies:** 3
**URL:** https://discourse.openehr.org/t/links-between-data-elements-in-different-archetypes/146

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## Post #1 by @heather.leslie

I note the commentary in the specs on Links - [https://specifications.openehr.org/releases/RM/latest/common.html#_link_class](https://specifications.openehr.org/releases/RM/latest/common.html#_link_class).

However, despite feeling judged by the commentary :slight_smile:, I have what appears to be a non-sensible use case where we are curious about the possibility of establishing a link between source clinical data (ie captured using the CKM archetypes designed for clinical recording) and corresponding registry data in a legacy, or integration, registry-specific archetype (either an identical data point  or even an appropriate mapping to a higher level category). For example a BP of 140/90 to a category of 'Raised BP'. Implementation is not yet decided, potentially in either the same or different CDRs.

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## Post #2 by @yampeku

Only limitation right now is that target is DV_EHR_URI, so as long as that kind of URI can be defined from your legacy source (and somehow understood by it) I think it's supported.

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## Post #3 by @thomas.beale

I would have thought the default option would just be to use a `DV_URI` data item, which can point to anything that a URI can be obtained for. `LINK` as originally conceived was intended for a category of 'semantic' links reflecting relationships between clinical recordings, such as 'indicated by', 'test result for' and so on. I have always thought this was somewhat subjective (it's from CEN 13606, GEHR etc), and today I would probably suggest we tighten the definition of when LINK applies, e.g. to clinical process relationships. It's also somewhat different from just embedding a `DV_URI` in the data. The latter acts like an in-place reference; a `LINK` can hang off any larger object, e.g. the whole `OBSERVATION`.

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## Post #4 by @sebastian.iancu

@thomas.beale, a bit off-topic but perhaps it will not harm to remind here that restricting LINKs to only EHR_URIs is also an issue of https://openehr.atlassian.net/browse/SPECPR-281.
I think LINK should allow (inner) DV_URI to link only archetyped objects (including those from demographics).

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**Canonical:** https://discourse.openehr.org/t/links-between-data-elements-in-different-archetypes/146
**Original content:** https://discourse.openehr.org/t/links-between-data-elements-in-different-archetypes/146