Contextual Policy defines control of access according to its context. Contextual Policy can modify Initiator-based Policy or Resource-based Policy. Context rules may define the entire policy in effect. Contextual information is information about or derived from the context in which an access request is made (e.g., time of attempted access, location of the accessor, route of access). Rules concerning contextual information are most often used in conjunction with other access control schemes (e.g., label-based scheme, capability scheme, ACL scheme), but they may be used alone to create a context-based access control scheme. [ISO 10181-3]