This Data Item Description (DID) contains the format and content preparation instructions for the data generated to support operation and maintenance of a subsystem for operations and maintenance personnel and in conjunction with accompanying equipment technical manuals. The information shall describe the subsystem in terms of functional signal flow, include operating instructions organized by subsystem operating positions. Maintenance instructions shall include text and illustrative material sufficient to perform subsystem preventative and corrective maintenance. Troubleshooting information shall be sufficiently complete to enable maintenance technicians to isolate fault to the subsystem or equipment (black box) level. Subsystem manuals shall contain the element of information described in the following paragraphs, supplemented but such illustrative and tabular material as is necessary to support the required data.