Agreed.  The discussion around use of effective [x] is ongoing in other workgroups as well.  Cognitive status will add additional guidance related to the definition of clinically relevant as follows: Clinical relevant time for an assessment such as cognitive assessments performed with structured evaluation tools is the time the evaluation occurs, i.e., when the clinician obtains the answers entered in the tool. However, the only timing available may be when then tool is completed by the clinician. That timing is generally documented as a point in time (dateTime). The use of effective [x] and dateTime versus Period is subject to implementer workflow and needs.  In most situations, an observation is considered as a point in time, even if the assessment occurred over a period of time.  Period is included in this implementation guide to provide additional flexibility for specific use cases.  However, it is expected most observations will be recorded using DateTime.  Furthermore, any retrieval of information should return the relevant if DateTime is requested, even if the original observation was recorded as a period.  Some implementers may choose to use additional functions in there retrieves to 'normalize' intervals, as is done in CQL.