This standard establishes the format of information on 12.65 mm instrumentation magnetic tape cassettes. It specifies the dimensions and locations of helical data and control tracks. It defines the format and recording requirements of the data blocks forming the helical data track containing digital instrumentation and other associated data, and specifies the content, format, and recording method for the control track. The physical requirements, magnetic requirements, and test methods for the magnetic tape and tape cassette are not specified in this standard, but can be found in the references or in the technical literature. No licenses for patented or copyrighted features are required to implement compliance with this standard. All dimensions given are metric.