A printer specifies at least one arbitrary option out of a plurality of options displayed on a display screen as a tentative option, determines the tentative option as a determined option, and performs printing based on the determinate option. The degree of contamination of the filter media is analyzed before the filter is carried into the cleaning apparatus. A semiconductor substrate non-removed section is formed under the gate insulation film, and semiconductor substrate removed regions are formed around the non-removed section by etching. In response to determining that a medium utilization of a network interface exceeds a corresponding medium utilization threshold, the network device determines whether one of its network interfaces originates a packet stream with the greatest stream medium utilization value for a selected priority class.