An optical system includes a first optical group configured to form, at a first intermediate image plane, a first intermediate image of an object disposed at an object plane; a second optical group and a third optical group configured to form, at an image plane, a final image of the object based on the first intermediate image. Each stepped first ridge has a first portion proximal the substrate surface with a pair of first opposed lateral walls terminating in a plateau, and a second portion terminating in a ridge tip. Special instructions may mark the boundaries of a transaction and identify memory locations applicable to a transaction. The low-level component operates at a higher frequency, such as the frame refresh rate of the graphics subsystem, to process the data structures into constant output data for the graphics subsystem. Consumer may download products and information from a single file within the promoterseller’s website or web page.