ISO 22600 specifies a Role as a "set of competencies and/or performances which is associated with a task". A Security Role defines a named group of policies (authorization, obligation, delegation and refrain policies) that can be managed, assigned, and revoked together for convenience of use rather than managing these policies individually. For example, at a given organization, all nurses (functional role) may have the same privileges and responsibilities conveyed through six policies. A nurse acting as the charge nurse (a structural role) may then have additional privileges based on two other policies. This class is used to enumerate the policies associated to the nurse role and the charge nurse role.