Usage of Compositoin.Category

Thomas Beale thomas.beale at
Fri Mar 11 16:26:33 EST 2016


yes, this is a reasonable way of looking at things, and it is the way 
AQL currently works. There is talk of adding a new operator to follow 
links, but we need to invent a way to mark the returned data as being 
targets of references rather than primary in this case.

The reason to allow this kind of reference following is to enable 
assembling the logical contents of e.g. discharge summary into a 
standalone package to eg. send in an Extract or process in some other 

So I would modify your final statement and say that AQL should normally 
be about data as they are recorded, with reference following having 
special handling.

- thomas

On 11/03/2016 02:39, Ivar Yrke wrote:
> Hi
> An interesting discussion that touches the very concept of structured information, in my opinion. I wonder if the suggested solution looks at the problem from the best angle. So here is my angle:
> As a person with some SQL experience I would expect an AQL to return ONLY primary content unless told otherwise. Any content that lives in a Composition as a link I would not expect to see in that Composition as an entry. Resolving links is a task for the level "above" (rendering on a screen etc.). I can see that there possibly are needs for an AQL that resolves links, but I would rather see this as the special case, much like joining in foreign keys in SQL is an explicit decision (the SQL analogy have some obvious flaws!)
> Why is this important? Because showing linked information in compositions where they were not originally recorded creates doubt about the origin of the information (source of truth). The duplication that Bjørn wants to solve is a symptom of un unhealthy structure that undermines an essential aspect of structured information. If a summary composition, like a discharge letter, only links information from other composition, there should be no duplication. So there should not be any need for later  special handling. There should be no problem to solve (well, there would be the need for the optional resolving, but this would be a feature rather than a problem).
> AQL should relate only to the data and how they are recorded, not to how they are used.
> With regards,
> Ivar Yrke
> Senior systemutvikler
> Telephone +47 75 59 24 06
> Mobil +47 90 78 89 33
> -----Original Message-----
> From: openEHR-technical [mailto:openehr-technical-bounces at] On Behalf Of Bjørn Næss
> Sent: 10. mars 2016 20:33
> To: For openEHR technical discussions <openehr-technical at>
> Subject: SV: Usage of Compositoin.Category

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