Overview
ISO/IEC 15895:1999 - Information technology - Data interchange on 12,7 mm 128-track magnetic tape cartridges - DLT 3‑XT format - defines the physical, magnetic and logical characteristics required to enable reliable interchange of 12.7 mm (nominal) 128‑track DLT 3‑XT magnetic tape cartridges between drives. The standard covers cartridge and tape mechanical dimensions, magnetic recording parameters, a tape layout and data format (including CRC/ECC rules), and environmental, testing and handling recommendations. It is intended to ensure physical and data interoperability among media, drives and systems.
Key topics and technical requirements
- Media geometry and materials
- Nominal tape width: ~12.7 mm (specified as 12.649 mm ±0.010 mm)
- Tape length: 560 m ±1 m; total thickness: 8.6 µm to 9.2 µm
- Base film (e.g., PET) with ferromagnetic coating and conductive back coat
- Mechanical tolerances and tape quality
- Limits on discontinuities, longitudinal curvature, cupping, out‑of‑plane distortion
- Surface roughness, coating and layer adhesion, tensile and flexural properties
- Environmental and safety
- Test conditioning: 23 °C ±2 °C, 40–60 % RH; operating: 10–40 °C, 20–80 % RH; storage: 16–32 °C
- Flammability and transport recommendations (annexes)
- Magnetic recording and signal characteristics
- Physical recording density, flux transition spacing, azimuth, channel skew, read signal amplitude
- Definitions such as Standard Reference Amplitude (SRA), Test Recording Current and Typical Field
- Tape format and data structure
- Tape layout: scratch, calibration, directory and data areas; 128 physical tracks arranged as logical track pairs
- Logical/physical block formats, preamble/sync/EDC/CRC/ECC, filler and end‑of‑data handling
- Normative annexes for CRC/ECC generation and MAP entry formats
- Calibration and reference media
- Master and Secondary Standard Reference Tapes (reference information provided in the standard)
Applications and who uses it
- Ensures data interchange and interoperability for organizations using DLT 3‑XT cartridges
- Primary users:
- Tape media manufacturers (quality and dimensional control)
- Tape drive and recorder manufacturers (mechanical and signal compatibility)
- Data centers, archives and backup solution providers (long‑term media interchange)
- Test laboratories and compliance auditors (conformance testing to mechanical, magnetic and data‑format requirements)
- Useful for migration planning, media qualification, and archival policy documentation.
Related standards
- ISO 1001 (Magnetic Tape Labelling) - recommended for full interchange
- ISO/IEC 14833 - earlier magnetic tape cartridge specification referenced by the introduction
- Originally prepared as ECMA‑258 and adopted via ISO/IEC JTC 1
Keywords: ISO/IEC 15895:1999, DLT 3‑XT, 12.7 mm magnetic tape, 128‑track, tape cartridge standard, data interchange, magnetic tape format, tape recording characteristics.