Unless I am missing something, the fragment items[at0001] cannot appear more than once /relative to any given archetype/. Here, it is relative to 'a', i.e. openEHR-EHR-CLUSTER.laboratory_test_analyte.v1. Within the same archetype, you cannot have other items[xxx] such that the xxx are not unique, even if there are multiple 'items' attributes down the containment graph. From different archetypes you can, but there is no difficulty for the AQL processor to disambiguate these.

On 26/04/2019 12:27, Georg Fette wrote:
Is it allowed to use an element that is allowed to appear multiple times within a path ?
For example in the query

SELECT a/items[at0001]/value
    FROM EHR e
        CONTAINS CLUSTER a[openEHR-EHR-CLUSTER.laboratory_test_analyte.v1]

the field items[at0001] may appear 0..* times. Thus the access to the value field is not properly defined from a type checking point of view. Does the AQL specification allow such constructs and how is this situation interpreted ?

Thomas Beale
Principal, Ars Semantica <http://www.arssemantica.com>
Consultant, ABD Project, Intermountain Healthcare <https://intermountainhealthcare.org/> Management Board, Specifications Program Lead, openEHR Foundation <http://www.openehr.org> Chartered IT Professional Fellow, BCS, British Computer Society <http://www.bcs.org/category/6044> Health IT blog <http://wolandscat.net/> | Culture blog <http://wolandsothercat.net/> | The Objective Stance <https://theobjectivestance.net/>
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