User-facing apps often need to know things like: - "who are the patients I'm seeing today," - "who are the patients I'm responsible for in the hospital right now," - "who are the patients in this ward." This is core functionality supported by existing EHR systems. In FHIR, various methods have been used such as the standard search API or assembling the List or Group resource. However, no standard or guidance for creation of and manipulation of patient lists currently exists. Support interoperable and standard exchange of existing EHR supported "user-facing lists". - user-facing lists include both "system-maintained" and "user-maintained"(which are entirely ad-hoc - the user explicitly selects and manages members) lists * Define a general framework using the FHIR API for exposing existing EHR user-facing patient lists so that EHR systems can expose any list they choose to define. * This API would allows user-facing apps to: 1. Discover user-facing lists - Search on existing list using very limited set of parameters such as "location characterstics" (for system-maintained lists) or Practitioner (for user-maintained list) 1. Fetch the List allowing app to enumerate members of a user-facing list 1. Provide a framework to convey other details about the members of a list Writing, creating or managing a patient list is out of scope for this IG. Fetching client defined patients lists is also out of scope.