Indicates mode of accounting records to be generated. 'start-stop' : In this mode, device sends a message to the configured accounting server indicating start of the accounting process for a client when a client logs in. It sends another message to the accounting server indicating end of the accounting process after the client logs out. 'stop-only' : In this mode, device sends a message to the configured accounting server indicating end of the accounting process after a client logs out. No message is sent when the client logs in.