QuestionnaireResponse.authored defined as date answers were gathered. Some questionnaires will be completed over more than one day but generally recorded as the date finalized and completed. However, the current definition suggests that the date is not when completed but when gathered which may be a period of time. Although responses are rarely recorded with the time period over which the data are collected, the FHIR Resource should be very specific and avoid any potential ambiguity. Suggest changing the definition to "data answers were validated and completed" - I realize this suggestion will take discussion but I think it will help to avoid potential ambiguity.