Hi! I hear of a lot of interesting off-line discussions regarding the openEHR RM object named "LINK". I guess they have not yet reached the mailing list because of time restrictions and/or the exploratory/initial nature of the discussions. But now let's get more good brains involved...
Just to make sure we talk about the same thing, it is the class LINK described in section 3.2.4 in http://www.openehr.org/releases/1.0.2/architecture/rm/common_im.pdf and in XML schema http://www.openehr.org/releases/1.0.2/its/XML-schema/documentation/Structure.xsd.html#h518145503 (An excerpt from the spec is attached by the end of this mail) Some of the interesting bits I've picked up so far from discussions: - Maybe it would be a good idea to make LINK inherit from LOCATABLE and thus become archetypable in itself - Tooling support for using LINK in archetypes is currently poor or non existent - There is very little (if any) reported usage experience of LINK in openEHR - I believe the NHS has somewhat explored LINK usage in LRA using ISO 13606 - If archetyping LINKS, then it would in _some_ cases be desirable to be able restrict the type of the "target", especially defining what archetypes the target objects must adhere to (similar to the archetype slot mechanism). Please fill in with nore details and thoughts. Implementers, would it have a big impact on your implementations if LINK was made LOCATABLE? (Let's say in v 1.0.3) I wonder, is it currently safe to archetype the DV_EHR_URI used in the "target" attribute of LINK just using a string matching pattern or do we need additional mechanisms? The URI value represents an identifier of some node inside a versioned object, do string patterns matching DV_EHR_URI values cover for all kinds of target range restrictions we'd likely want to express if archetyping LINKs? Maybe they actually do work using wildcards in the right places? How tricky will it be to implement that constraint checking at runtime data creation? Best regards, Erik Sundvall erik.sundvall at liu.se http://www.imt.liu.se/~erisu/? Tel: +46-13-286733 Excerpts from section 3.2.4 in common_im.pdf: Purpose: The LINK type defines a logical relationship between two items, such as two ENTRYs or an ENTRY and a COMPOSITION. Links can be used across compositions, and across EHRs. Links can potentially be used between interior (i.e. non archetype root) nodes, although this probably should be prevented in archetypes. Multiple LINKs can be attached to the root object of any archetyped structure to give the effect of a 1->N link - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Use: 1:1 and 1:N relationships between archetyped content elements (e.g. ENTRYs) can be expressed by using one, or more than one, respectively, DV_LINKs. Chains of links can be used to see ?problem threads? or other logical groupings of items. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - MisUse: Links should be between archetyped structures only, i.e. between objects representing complete domain concepts because relationships between sub-elements of whole concepts are not necessarily meaningful, and may be downright confusing. Sensible links only exist between whole ENTRYs, SECTIONs, COMPOSITIONs and so on. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Attributes : [1..1] meaning: DV_TEXT Used to describe the relationship, usually in clinical terms, such as ?in response to? (the relationship between test results and an order), ?follow-up to? and so on. Such relationships can represent any clinically meaningful connection between pieces of information. Values for meaning include those described in Annex C, ENV 13606 pt 2 [11] under the categories of ?generic?, ?documenting and reporting?, ?organisational?, ?clinical?, ?circumstancial?, and ?view management?. [1..1] type: DV_TEXT The type attribute is used to indicate a clinical or domain-level meaning for the kind of link, for example ?problem? or ?issue?. If type values are designed appropriately, they can be used by the requestor of EHR extracts to categorise links which must be followed and which can be broken when the extract is created. [1..1] target: DV_EHR_URI The logical ?to? object in the link relation, as per the linguistic sense of the meaning attribute. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - End of excerpts from section 3.2.4 in common_im.pdf
