cts2/cts2-specification — Issue #80: Multiply the object instances in order to represent the correct information
Author: aestelrich
Created: 2012-03-07 15:47:06+00:00
State: open

« CTS2 differentiates between a simple resource reference, such as a code system, code system version, value set, etc. and a reference to an Entity - a class, predicate or individual. Simple resource references are identified by a single URI. Entity references, however, are subdivided into two parts - an scoping name space and a name that is unique within the context of the namespace. ».

The identification of an object seems to be done via a combination between a Resource and an Entity. This construction does not cover easily the complexity of the identification of the objects as required by the HL7 SFM - for example a Code System and a Code System Version in the SFM have a compositional relationship - i.e. the Code System Version cannot exist independently from the Code System. In the PIM a Code System version is a resource which points to the Resource Code System; however this construction implies that a Code System Version has a unique resource identifier which is often not the case. This can also be seen through another example. In the SFM there are objects whose identification is much more complex such as the value of an attribute of a LOINC code. In order to correctly identify this value, we need to know at least four pieces of identification: the OID of the Code System, the LOINC code itself, the identity of the attribute, and the version of the Code System. The construct in the PIM leads to multiplying the object instances in order to represent the correct information.