Overview
ISO/IEC 15731:1998 specifies a standardized physical and magnetic tape format for information interchange using a 12.65 mm wide magnetic tape cassette - the Digital Tape Format‑1 (DTF‑1) using helical‑scan recording. The standard defines two cassette sizes (Type S and Type L), tape materials and dimensions, recording methods, track formats (helical and longitudinal), signal quality metrics and reference calibration tapes (MSRT/SSRT). The format supports variable‑length logical records, high‑speed search and registered algorithms for lossless data compression.
Key topics and technical requirements
- Cassette case and mechanical specs: detailed dimensional, datum, window, label, reel, guiding groove and write‑protect requirements for Type S and Type L cassettes.
- Tape physical characteristics: tape width/length, thickness, curvature, tensile strength, splice and layer adhesion, coating resistance and wind.
- Magnetic recording characteristics: Average Signal Amplitude (ASA), signal‑to‑noise (S/N), resolution, missing‑pulse limits and erasure performance.
- Track format and geometry:
- Helical track sets (Track Set = four consecutive helical tracks) with defined track angle, width, pitch and azimuth.
- Longitudinal tracks (Control Track, Time Code Track) with format, alignment and amplitude requirements.
- Recorded information and logical organization: Block Management Table (BMT), logical volumes, logical track set IDs, product code arrays, sync blocks, sectors and file append/overwrite behaviors.
- Calibration and reference tapes:
- Master Standard Reference Tape (MSRT) and Secondary SR tapes (SSRT) for traceable calibration of Standard Reference Amplitude (SRA) and Test Recording Currents (TRC).
- TRC1 = 1.1 × Ir1; TRC2 = 1.0 × Ir2 (as defined in the standard).
- Conformance criteria: requirements for magnetic tape cassettes, generating systems and receiving systems; claims of conformance must declare supported cassette types and implemented registered compression algorithm(s).
- Ancillary requirements: environmental and safety testing, flammability, transportation recommendations and measurement methods (e.g., S/N measurement in Annex A).
Applications and who uses it
- Tape drive and media manufacturers: for interoperable cassette and tape production, mechanical tolerances and magnetic performance.
- Archive and data‑center operators: to ensure reliable interchange, long‑term retention and high‑speed searchability across systems.
- Test laboratories and calibration services: for traceable amplitude and signal quality calibration using MSRT/SSRT.
- System integrators and software vendors: to implement file/volume structure, block management and compression conformance for interchangeability.
Related standards
- ISO 1001 (file structure and labelling for magnetic tapes)
- ISO/IEC 11576 (procedure for registration of lossless compression algorithms)
- IEC 950 (safety of information technology equipment)
- SMPTE timecode (time and control code for tape)
Keywords: ISO/IEC 15731:1998, DTF‑1, 12.65 mm magnetic tape cassette, helical scan recording, tape format, MSRT, SSRT, SRA, TRC, tape interoperability.
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