The Instructional Management System (IMS) developed by the Southwest Regional Laboratory (SWRL) processes student and teacher-generated data through the use of an optical scanner that produces a magnetic tape (Scan Tape) for input to IMS. A series of computer routines, OPSN, preprocesses the Scan Tape and prepares the data for transmission to the central computer facility for further processing. This document is a functional description of the OPSN computer software. Included are (1) a general discussion of the editing and data conversion process, (2) explanations of the various input forms, (3) examples of the data conversion tables used within the computer programs, (4) the field definitions of the scan sheets, and (5) a flowchart of the entire preprocessing system. (DGC)