An etching gas for etching an oxide film formed on a substrate, includes a main gas composed of an unsaturated fluorocarbon-based gas; and an additive gas composed of a straight-chain saturated fluorocarbon-based gas expressed by CxF. The imaging jobs include diverse imaging tasks that can be constructed in a single program unit. The elongated cavity in the trailing edge may have one or more orifices in the rib on the upstream side of the cavity. Also provided are methods of modulating an optical signal utilizing such electro-optic modulators. Alternatively, the controller adjusts a rate of delivery of the metering device based on the calculated flow rate to cause the dispensing element to dispense the desired amount of material along the predetermined pattern. A diagnostic partition is established between the starting sector address and the ending sector address of the first user partition in the hard disk drive.