This case-sensitive code system http://hl7.org/fhir/us/pacio-pfe/CodeSystem/pfe-functioning-cs defines the following code:

Code	Display	Definition
functioning	Functioning	Functioning is an umbrella term for body function, body structures, activities, and participation in societal roles. An individual's functioning and engagement represents a dynamic interaction between their health condition, environmental factors, and personal factors. Taking a broad view of health that encompasses physical, mental, and social well-being, includes optimizing functioning and engagement as a component of optimizing their health. Characterizing an individual's functioning and engagement includes both understanding the severity of an individual's signs, symptoms, impairments and limitations, and how they correspond with day-to-day activities. Functioning and engagement also serve as a key health outcome within health care.