Agreed. Definition added. Conformance The conformance verbs - SHALL, SHOULD, MAY - used in this guide are defined in FHIR Conformance Rules. Must Support When querying and reading the Plan-Net Profiles defined in this IG, Must Support on any profile data element SHALL be interpreted as follows: Health Plan API Requirements Health Plan API actors SHALL be capable of populating all data elements as part of the query results. In situations where information on a particular data element is not present and the cardinality is 0.. , the Health Plan API actors SHALL NOT include the data elements in the resource instance returned as part of the query results. In situations where information on a particular data element is not present and the cardinality is >0.. SHALL send the reason for the missing information using values (such as nullFlavors) from the value set where they exist or use the dataAbsentReason extension. Application Requirements Application actors SHALL be capable of processing resource instances containing the data elements without generating an error or causing the application to fail. Application actors SHOULD be capable of displaying the data elements for human use or storing the information for other purposes. When querying Health Plan API actors, Application actors SHALL interpret missing data elements within resource instances as data not present in the Health Plan API actors system. Consumer App actors SHALL be able to process resource instances containing data elements asserting missing information. Conformance to US Core Profiles Any actor acting as a Health Plan API actor in this IG SHALL: Be able to populate all profile data elements that have a minimum cardinality >= 1 and/or flagged as Must Support as defined by that profiles StructureDefinition. Conform to the US Core Server Capability Statement expectations for that profiles type. Any actor acting a FHIR Client in this IG SHALL: Be able to process and retain all profile data elements that have a minimum cardinality >= 1 and/or flagged as Must Support as defined by that profiles StructureDefinition. Conform to the US Core Client Capability Statement expectations for that profiles type.