Disclosed herein, among other things, are method and apparatus for managing priority in a standardized test and survey imaging system. A test signal is applied to the power engineering device, and this test signal, starting from an initial value, rises steadily and monotonically to a predetermined final value, and retains this final value over a predetermined time interval. In each slit there is arranged a captive movable rectangular metal slug whose position along the slit’s length can be manipulated by a tool that engages the slug when the tool is introduced into a radial passageway that connects the slit with an access hole in the filter’s housing.