A positive resist composition is provided comprising a polymer comprising recurring styrene units having an ester group bonded to a CF3\u2014C\u2014R3 group such as 1,1,1,3,3,3-hexafluoro-2-propanol and having a Mw of 1,000-500,000. A sensor is connected on the top surface of the can so as to detect the position of the lid. This makes the online optimization method less sensitive to system noise and capable of being adapted to handle different workloads. When the result of monitoring is that the maintenance time of an image forming apparatus has been reached, scheduling is carried out to reassign unprocessed jobs out of the assigned jobs to image forming apparatuses other than the image forming apparatus for which the maintenance time has been reached. Another preferred embodiment includes a mask manufacturing method further including a mask step.