A method of managing operations performed in a client-server environment comprises receiving a set of commands; executing a first command in the set, wherein the first command is associated with a second command; and executing the second command, in response to determining that a first event has occurred. For example, methods and apparatus adjust one of a minimum set point and a maximum set point in response to a user manipulation of a component of a light management system. Thereby, system transmission requirement is satisfied, and complexity of transmitting end is relatively lowered. The digital MFP retrieves from the flash memory the user ID and the password that form a pair with the abbreviated code entered by the operator using the operation unit, and acquires authentication success or failure information with respect to the retrieved user ID and the password from an authentication server. Protrusions for guiding the cam followers are provided corresponding thereto at an outer periphery of the intermediate connecting member, upper surfaces of the protrusions being inclined.