An approach for managing access to electronic documents uses document retention and document security policies. The memory element stores a transaction history for the account, an incentive previously offered to the account, and an artificial intelligence program. A portion of each fitting groove and a portion of the corresponding projecting portion, the portions contacting each other, respectively have arc surfaces, and a portion of each projecting portion and a portion of the corresponding cover member, the portions contacting each other, respectively have flat surfaces. In one embodiment, the utensil is a chopstick, and preferably is provided as a pair of two such chopsticks. In another step, an exemplary embodiment provides a public key of a subscriber if the topic policy directs that the subscriber receive a message in encrypted form. The pump includes a piston installed in the bore in a reciprocating movable manner and defining an inlet path therein, an inlet valve to open or close an exit-side end of the inlet path according to a position of the piston, and an outlet valve provided at one side of the bore, operations of the inlet and outlet valves being contrary to each other.