"Specifies an event that may occur multiple times. Timing schedules are used for specifying when events are expected or requested to occur, and may also be used to represent a schedule that was followed for past events. A Timing schedule can be a list of events and/or criteria for when the event happens, which can be expressed in a structured form and/or as a code. When both event and a repeating specification are provided, the list of events should be understood as an interpretation of the information in the repeat structure." - HL7 FHIR, Timing

"Specifies clinical/business/etc. metadata that can be used to retrieve, index and/or categorize an artifact. This metadata can either be specific to the applicable population (e.g., age category, DRG) or the specific context of care (e.g., venue, care setting, provider of care)." - HL7 FHIR, UsageContext

A specialization of Address that is used for addresses in the United Sates. Note that the stateOrTerritory property may only contain a code for a U.S. State, territory, or military postal region (APO). The purpose of this sub-type is to provide a mechanism to add the stateOrTerritory property and to bind it to the valueset of codes valid for United States mail.