This case-sensitive code system http://hl7.org/fhir/us/davinci-atr/CodeSystem/davinci-group-characteristic-codes defines the following codes:

Code	Display	Definition
location	Location	Members (Patients) whose care is at the location specified by the value which references the Location resource representing the physical structures managed/operated by an organization (e.g., a ward, building, clinic, etc)
careteam	CareTeam	Members (Patients) who are under the care of the care-team specified by the value which references the CareTeam resource representing the care-team. (e.g., Respiratory Therapy CareTeam, CareTeam blue , etc)
organization	Organization	Members (Patients) whose care is at the organization specified by the value which references the Organization resource representing the organization. (e.g., Burgess Medical Group)
practitioner	Practitioner	Members (Patients) who are under the care of the practitioner specified by the value which references the Practitioner resource representing the practitioner. (e.g., Dr Leung)
attributed-to	Attributed to a specific Provider, Organization etc.	Members (Patients) who are attributed to a specific Organization or Provider by the value which references the Practitioner or Organization resource (e.g., Neighborhood Hospitals or Dr Leung). This is different from the practitioner code which may be shared by patients for any reason beyond attribution such as PCP etc.