Talk:Inert vs. descriptive properties of Acts
Looking at this topic, it appears that:
All subsequent attributes extended from Act on Observation, Supply, SubstanceAdministration, Procedure and PatientEncounter are descriptive. This makes sense because other properties on classes that extend from Act would not seem to need to add inert properties (metadata about the act itself) that doesn't already appear on act.
Looking specifically at Observation: methodCode and targetSiteCode further subclassify code, which is descriptive, making these descriptive. Value is clearly descriptive. Finally, interpretationCode is a summarization of descriptive properties (including value), and therefore also descriptive.