ISO/IEC 15731:1998

Information technology - 12,65 mm wide magnetic tape cassette for information interchange - Helical scan recording - DTF-1 format

Technologies de l'information — Cassette de bande magnétique de 12,65 mm de large pour l'échange d'information — Enregistrement par balayage en spirale — Format DTF-1

General Information

• Status: Published
• Publication Date: 20-May-1998
• ICS: 35.220.23 - Cassettes and cartridges for magnetic tapes
• Technical Committee: ISO/IEC JTC 1/SC 23 - Digitally recorded media for information interchange and storage
• Drafting Committee: ISO/IEC JTC 1/SC 23 - Digitally recorded media for information interchange and storage
• Current Stage: 9093 - International Standard confirmed
• Start Date: 21-Aug-2020
• Completion Date: 30-Oct-2025

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.

Standards Content (Sample)

INTERNATIONAL
ISOAEC
STANDARD 15731
First edition
1998-05 15
Information technology - 12,65 mm wide
magnetic tape cassette for information
interchange - Helical scan recording -
DTF-1 format
Technologies de Yin formation - Cassette de bande magrktique de
12,65 mm de large pour khange d ’information - Enregistrement par
balayage en spirale - Format DTF- I
Reference number
ISO/I EC 15731: 1998(E)
Contents
Section 1 - General
1 Scope
2 Conformance
2.1 Magnetic tape cassette
2.2 Generating system
2.3 Receiving system
3 Normative references
4 Definitions
4.1 Absolute block number
4.2 a.c. erase
4.3 algorithm
4.4 Append file
4.5 Append volume
4.6 Average Signal Amplitude (ASA)
4.7 azimuth
4.8 back surface
4.9 bit cell
4.10 block
4.11 Block Management Table (BMT)
4.12 byte
4.13 cassette
4.14 compressed data
4.15 Control Track
4.16 flux transition position
4.17 flux transition spacing
4.18 Logical track set ID
4.19 Logical volume
4.20 magnetic tape
4.21 Master Standard Reference Tape (MSRT)
4.22 physical recording density
0 ISO/IEC 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
ISO/IEC Copyright Office l Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
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0 ISOIIEC
4.23 Reference Field (RF)
4.24 Secondary Standard Reference Tape (SSRT)
4.25 Standard Reference Amplitude (SRA)
4.26 Standard Reference Current (Ir)
4.27 Tape Reference Edge
4.28 Test Recording Current (TRC)
4.29 track
4.30 track angle
Track Set
4.31
4.32 Typical Field (TF)
4.33 Unique Identifier (UID)
4.34 word
5 Conventions and notations
5.1 Representation of numbers
5.2 Names
6A cronyms
7 Environment and safety
7.1 Testing environment
7.2 Operating environment
7.3 Storage environment
7.4 Transportation
Safety
7.5
7.6 Flammability
Section 2 - Requirements for the case
8 Dimensional and mechanical characteristics of the case
8.1 General
8.2 Type S cassette
8.2.1 Overall dimensions
8.2.2 Holding areas
8.2.3 Window
8.2.4 Label areas
8.2.5 Datum areas and datum holes
8.2.6 Support areas
8.2.7 Guiding grooves
8.2.8 Recognition holes
8.2.9 Write-inhibit plug
8.2.10 Pre-positioning surface
8.2.11 Cassette lid
8.2.12 Cassette reel lock
8.2.13 Reel access holes
8.2.14 Reels
8.2.15 Position of the tape in the case
8.2.16 Tape path zone
. . .
0 ISO/IEC
8.2.17 Tape access cavity
8.3 Type L cassette
8.3.1 Overall dimensions
8.3.2 Holding areas
8.3.3 Window
8.3.4 Label areas
8.3.5 Datum areas and datum holes
8.3.6 Support areas
8.3.7 Guiding grooves
8.3.8 Recognition holes
8.3.9 Write-inhibit plug
8.3.10 Pre-positioning surface
8.3.11 Cassette lid
8.3.12 Cassette reel lock
8.3.13 Reel access holes
8.3.14 Reels
8.3.15 Position of the tape in the case
8.3.16 Tape path zone
8.3.17 Tape access cavity
8.3.18 Cavity for compatibility with Type S cassette
Section 3 - Requirements for the unrecorded tape
9 Mechanical, physical and dimensional characteristics of the tape
9.1 Materials
9.2 Tape length
9.3 Tape widths
9.4 Width and position of splicing tape
9.5 Discontinuity
9.6 Tape thickness
9.7 Longitudinal curvature
9.8 Out-of-plane distortions
9.9 Coating adhesion
9.10 Layer-to-layer adhesion
9.11 Tensile strength
9.11.1 Breaking strength
9.11.2 Yield strength
9.11.3 Strength of Splice
9.12 Residual elongation
9.13 Electrical resistance of the coated surfaces
9.14 Tape wind
10 Magnetic recording characteristics
10.1 Typical Field TFl
10.2 Average Signal Amplitude(ASA)
10.3 Resolution
10.4 Signal-to-noise ratio (S/N)
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10.5 Ease of erasure
10.6 Tape quality
10.6.1 Missing pulses
10.6.2 Missing pulse zone
10.7 Inhibitor tape
Section 4 - Requirements for an interchanged tape
11 Format for helical tracks
11.1 General description of the write data path
11.2 Formation of a Logical Track Set
11.2.1 Types of information track sets
11.2.2 Generation of a Logical Track Set
11.2.3 Subcode data field
11.2.4 BMT
11.2.5 Data and information field definitions
11.3 Track Set information
11.3.1 Loading the Product Code Arrays
11.4 Product code array processing
11.4.1 Error correction method
11.4.2 Error correction coding for Cl Parity
11.5 Track assignments
11.5.1 Sectors
11.5.2 Sync Blocks
11.5.3 Track interleave
11.5.4 Track Sync Blocks
11.5.5 Byte interleave across Sync Blocks
11.5.6 Randomization
11.6 Formation of the contents of a helical track
11.6.1 Sector details (figure 50)
11.7 Channel bit coding (annex B)
11.7.1 General
11.7.2 Interleaved-NRZ 1
12 Track geometry
12.1 General
12.2 Helically recorded tracks
12.2.1 Location of the tracks
12.2.2 Track width
so
12.2.3 Track angle
12.2.4 Track pitch
12.2.5 Location of elements in the helical track
12.2.6 Location of the Data Area Reference Point
12.2.7 Straightness of tracks
12.2.8 Azimuth angles
12.2.9 Tracking Pilot Signal (TPS)
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12.2.10 Amplitude of servo signals
12.3 Longitudinal tracks geometry
12.3.1 Control Track
12.3.2 Time Code Track signals recording position
13 Method of recording helical tracks
13.1 Physical recording density
13.2 Record current optimization
13.3 Efficiency of erasure
14 Method of recording longitudinal tracks
14.1 Overview
14.2 Control Track
14.2.1 Signal
14.2.2 Polarity of magnetisation (figure 53)
14.2.3 Alignment
14.2.4 Read signal amplitude
14.2.5 Quality of the Control Track
14.3 Time Code Track
14.3.1 Method of recording the Time Code Track
14.3.2 Physical recording density
14.3.3 Bit shift
14.3.4 Read signal amplitude
14.3.5 Quality of the Time Code Track
14.4 Format for the Time Code Track
14.4.1 Count bits
14.4.2 Phase bit
14.4.3 Synchronizing pattern
14.4.4 Supplemental Data
14.4.5 Extent of Time Code
Section 5 - Requirements for recorded information
15 Recorded information
15.1 Recording area (figure 54)
15.2 Magnetic tape layout (figure 55)
15.2.1 Valid data areas
152.2 Invalid data areas
15.3 Physical TSID
15.3.1 Structure surrounding the VSIT area
15.3.2 Structure of the DIT area
15.3.3 Structure of the User Data Area
Section 6 - Write operations
16 Write retry sequence
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17 Append file operation
17.1 Append volume
17.2 Append write
17.3 Overwrite
17.4 File extension
Annexes
A - Measurement of Signal-to-Noise Ratio
B - Representation S/9 coding patterns
C - Recommendations for Transportation
D - Inhibitor Tape
vii
Foreword
IS0 (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the
specialized system for worldwide standardization. National bodies that are members of IS0 or IEC participate in the
development of International Standards through technical committees established by the respective organization to deal with
particular fields of technical activity. IS0 and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non-governmental, in liaison with IS0 and IEC, also take part in the work.
In the field of information technology, IS0 and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft
International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the national bodies casting a vote.
International Standard ISO/IEC 1573 1 was prepared by ECMA (as Standard ECMA-248) and was adopted, under a special
“fast- track procedure ”, by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by
national bodies of IS0 and IEC.
Annexes A, and B form an integral part of this International Standard. Annexes C and D are for information only.
IS0 and IEC draw attention to the fact that it is claimed that compliance with this International Standard may involve the use
of patents concerning the Master Standard Reference Tape and Secondary Standard Reference Tape given in clause 4.
IS0 and IEC take no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured IS0 and IEC that he is willing to negotiate licences under reasonable and non-
discriminatory terms and conditions with applicants throughout the world. In this respect, the statement of the holder of this
patent right is registered with IS0 and IEC. Information may be obtained from:
Sony Corporation
Contracts and Licensing Division
Tokyo international
P.O. Box 5100 Tokyo
100-3 1 Japan
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights
other than those identified above. IS0 and IEC shall not be held responsible for identifying any or all such patent rights.
. . .
Vlll
INTERNATIONAL STANDARD 0 ISO/IEC ISO/IEC 15731:1998 (E)
Information technology - 12,65 mm wide magnetic tape cassette for information
interchange - Helical scan recording - DTF-1 format
Section 1 - General
1 Scope
This International Standard specifies the physical and magnetic characteristics of magnetic tape cassettes, using magnetic tape
12,65 mm wide so as to provide physical interchange of such cassettes between drives. It also specifies the quality of the
recorded signals, the recording method and the recorded format, called Digital Tape Format-l (DTF-l), thereby allowing data
interchange between drives by means of such cassettes. The format supports variable length Logical Records, high speed
search, and the use of a registered algorithm for data compression.
This International Standard specifies two sizes of cassette. For the purposes of this International Standard the larger cassette is
referred to as Type L, and the smaller as Type S.
Together with a standard for volume and file structure, e.g. IS0 1001, this International Standard provides for full data
interchange between data processing systems.
2 Conformance
Magnetic tape cassette
21 .
A claim of conformance with this International Standard shall specify the Type of cassette. It shall be in conformance with this
International Standard if
-
the case meets all the requirements of clause 4 and clauses 6 to 10 for that Type
-
the recording on the tape meets the requirements of clauses 11 to 17
22 . Generating system
A claim of conformance with this International Standard shall specify which Type(s) of cassette is (are) supported. A system
generating a magnetic tape cassette for interchange shall be in conformance with this International Standard if all the
recordings that it makes, meet the mandatory requirements of this International Standard. A claim of conformance with this
International Standard shall state whether or not one, or more, registered algorithm(s) is (are) implemented and, if so, the
registered number(s) of (all) the implemented algorithm(s).
23 . Receiving system
A claim of conformance with this International Standard shall specify which Type(s) of cassette is (are) supported. A system
receiving a magnetic tape cassette for interchange shall be in conformance with this International Standard if it is able to
handle any recording made on the tape according to this International Standard, and a claim of conformance shall state
whether or not one, or more, registered algorithm(s) is (are) implemented and, if so, the registered number(s) of (all) the
implemented algorithm(s).
3 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International
Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to
agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent
editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International
Standards.
Plastics - Determination of tensile properties.
IS0 527 (all parts),
File structure and labelling of magnetic tapes for information
IS0 1001:1986, Information processing -
interchange.
ISO/IEC 11576: 1994, Information technology - Procedure for the registration of algorithms for the lossless
compression of data.
IEC 950:1991, Safety of information technology equipment.
JIS-B-7502, Characteristics of plastic goods.
SMPTE timecode: (C98.12 : time and control code for video and audio tape for 525/60 television system).
OISOAEC
ISOLIEC 15731:1998 (E)
Definitions
For the purposes of this International Standard, the following definitions apply.
to each block, indicating that the block is the Nth block from
41 . Absolute block number: A number N allocated
the beginning of the Logical volume containing it.
42 . a.c. erase: A process of erasure utilizing alternating magnetic fields of decaying intensity,
43 . algorithm: A set of rules for transforming the logical representation of data.
44 . Append file: A new file added from the End of Data (EOD) of a Logical volume.
45 . Append volume: A Logical volume added after the last Logical volume recorded on the cassette.
output of a read head
46 . Average Signal Amplitude (ASA): The average peak-to-peak value of the signal
measured over a minimum of 1,40 mm of track, exclusive of missing pulses.
47 . azimuth: The angular deviation, in degrees of arc, of the recorded flux transitions on a track from the line normal
to the track centreline.
48 . back surface: The surface of the tape opposite to the magnetic coating used to record data.
49 . bit cell: A distance along the track allocated for the recording of a Channel bit.
block: A unit of data which is sent to the tape controller when a single write command is executed.
4.10
4.11 Block Management Table (BMT): A table included in each Track Set to manage blocks contained in that
Track Set.
4.12 byte: An ordered set of bits acted upon as a unit.
4.13 cassette: A case containing magnetic tape stored on twin reels.
compressed data: A representation of host-transmitted data after transformation by a data compression
4.14
algorithm.
4.15 Control Track: A track used for recording the servo control signals.
4.16 flux transition position: That point along a track on the magnetic tape that exhibits the maximum free-space
flux density normal to the tape surface.
4.17 flux transition spacing: The distance along a track between successive flux transitions.
Logical track set ID: The track set ID assigned to each track set containing data received from the host.
4.18
4.19 Logical volume: A data entity received by the generating system from the host.
4.20 magnetic tape: A tape which will accept and retain the magnetic signals intended for input, output, and storage
purposes.
4.21 Master Standard Reference Tape (MSRT): A tape selected as the standard for Signal Amplitude, Reference
Field, Resolution and Signal to Noise Ratio (S/N).
NOTE - The Master Standard Reference Tape has been established at SONY Corporation.
4.22 physical recording density: The number of recorded flux transitions per unit length of track, specified as flux
transitions per millimetre (ftpmm).
4.23 Reference Field (RF): The Typical Field of the MSRT. There are two Reference Fields:
RF1 is that for a helically recorded track
RF2 is that for a longitudinally recorded track.
4.24 Secondary Standard Reference Tape (SSRT): A tape the performance of which is known and stated in
relation to that of the MSRT.
NOTE - Secondary Standard Reference Tapes can be ordered under the Part Number SSRT-DTF- 1, from the Sony Corporation, Magnetic Product Group,
Data Media Sales Division, 6-7-3s Kitashinagawa, Shinagawa-ku, TOKYO 14 1, Japan. In principle such tapes will be available for a period of 10 years
from the publication of the International Standard. However, by agreement between IS0 and Sony Corporation, this period may be shortened or extended to
take account of demand for such SSRTs.
It is intended that these SSRTs be used for calibrating tertiary reference tapes for use in routine calibration.
4.25 Standard Reference Amplitude (SRA): The Average Signal Amplitude derived from the MSRT, using the
appropriate Test Recording Current and the appropriate physical recording density. There are three SRAs: SRAl is derived
OISOIIEC ISO/IEC 15731:1998 (E)
from a helically recorded track, recorded at 3 201 ftpmm with TRCl. SRA2 is derived from a longitudinally recorded track at
20,75 ftpmm with TRC2. SRA3 is derived from a helically recorded track, recorded at 800,3 ftpmm with TRCl.
Traceability to the SRAs is provided by the calibration factors supplied with each Secondary Standard Reference Tape.
4.26 Standard Reference Current (Ir): The current that produces a Reference Field. There are two Irs:
Irl is the current that produces RF1 on a helically recorded track.
Ir2 is the current that produces RF2 on a longitudinally recorded track.
4.27 Tape Reference Edge: The lower edge of the tape when the magnetic coating is facing the observer and the
supply reel is to the observer ’s right.
4.28 Test Recording Current (TRC): The current used to record an SRA. There are two Test Recording Currents:
TRC 1 is 1,l times Irl
TRC2 is 1 ,O times Ir2
4.29 track: A narrow, defined area on the tape along which a series of magnetic transitions may be recorded. A track
may be parallel to the Tape Reference Edge or at an angle to it.
4.30 track angle: The angle between the centreline of a helically recorded track and the Tape Reference Edge.
4.31 Track Set: A set of four consecutive helical tracks uniquely identified by a track set identification.
4.32 Typical Field (TF): There are two TFs:
In the plot of the ASA against the recording field:
TFl is the minimum recording field giving an ASA equal to 90 % of the maximum ASA at the physical recording density of 3
201 ftpmm on a helically recorded track.
TF2 is the value of the recording field for which the increase of ASA resulting from an increase of 1 dB of the recording field
falls to 05 dB at the physical recording density of 20,75 ftpmm on a longitudinally recorded track.
4.33 Unique Identifier (UID): A n unambiguous value uniquely distinct from every other UID.
4.34 word: A group (or set) of four &bit bytes, numbered 0 to 3, byte 3 being the most significant.
5 Conventions and notations
51 . Representation of numbers
l A measured value is rounded off to the least significant digit of the corresponding specified value. It implies that a specified
value of 1,26 with a positive tolerance of O,Ol, and a negative tolerance of 0,02 allows a range of measured values from
1,235 to 1,275.
l Letters and digits in parentheses represent numbers in hexadecimal notation.
l The setting of a bit is denoted by ZERO or ONE.
Numbers in binary notation and bit combinations are represented by strings of OS and 1s. Within such strings, X may be
used to indicate that the setting of a bit is not specified within the string.
l Numbers in binary notation and bit combinations are shown as Words with the MSB to the left, and with the msb in each
byte to the left.
l Negative values of numbers in binary notion are given in TWOS complement.
l In each field the data is processed so that the MSB is processed first. Within each byte the msb (numbered 7 in an 8-bit
byte) is processed first. This order of processing applies also to the data input to the Error Detection and Correction circuits
and to their outputs, unless otherwise stated.
52 . Names
The names of entities, e.g. specific tracks, fields, etc., are given with a capital initial.
6 Acronyms
Average Signal Amplitude
ASA
OISO/IEC
CRC Cyclic Redundancy Check
BMT Block Management Table
Bad Spot Table
BST
DIT Directory Information Table
DM Dummy Track
ECC Error Correcting Code
EOD End of Data
FIT File Information Table
LBOT Logical Beginning of Tape
LEOT Logical End of Tape
LIDT Logical ID Table
lsb Least Significant Bit
LSB Least Significant Byte
msb Most Significant Bit
Most Significant Byte
MSB
MSRT Master Standard Reference Tape
NEOT Near End of Tape
PBOT Physical Beginning of Tape
Physical End of Tape
PEOT
SRA Standard Reference Amplitude
SSRT Secondary Standard Reference Tape
TF Typical Field
TPS Tracking Pilot Signal
TRC Test Recording Current
TSID Track Set Identification
Unique Identifier
UID
UT Update Table
VEOV Virtual End of Volume
Volume Information Table
VIT
VSIT Volume Set Information Table
7 Environment and safety
The conditions specified below refer to ambient conditions immediately surrounding the cassette. Cassettes exposed to
environments outside these limits may still be able to function usefully; however, such exposure may cause permanent damage.
71 . Testing environment
Unless otherwise specified, tests and measurements made on the tape to check the requirements of this Standard shall be made
under the following conditions.
temperature 23 “C + 1 “C
relative humidity 48 % to 52 %
conditioning period before use 24 h min.
72 . Operating environment
Cassettes used for data interchange shall be operated under the following conditions:
temperature 5 ”Ct040 ”C
relative humidity 20 % to 80 % non-condensing
wet bulb temperature 26 “C max
The cassette shall be conditioned before use in the operating environment for a time at least equal to the period during which it
has been out of the operating environment, up to a maximum of 24 h.
NOTE - Rapid variations of temperature should be avoided.
OISO/IEC ISO/IEC 15731:1998 (E)
73 . Storage environment
The following conditions shall be observed for storage.
temperature: 5 “C to 32 “C
relative humidity: 20 % to 60 %
The stray magnetic field at any point on the tape shall not exceed 4 000 A/m. There shall be no deposit of moisture on or in the
cassette.
74 . Transportation
Recommended limits for the environment to which a cassette may be subjected during transportation, and the precautions to be
taken to minimize the possibility of damage, are provided in annex D.
75 . Safety
The cassette and its components shall satisfy the requirements of ECMA-129 when used in the intended manner or in any
foreseeable use in an information processing system.
76 . Flammability
The tape and the case components shall be made from materials which, when ignited from a match flame, do not continue to
burn in a still carbon dioxide atmosphere.
Section 2 - Requirements for the case
8 Dimensional and mechanical characteristics of the case
81 . General
The case of the cassette shall comprise
an upper half,
a lower half,
a lid pivotally mounted on the upper half
a latch mechanism for the lid
two reels for magnetic tape
a locking mechanism for the reels
a write-inhibit mechanism
recognition holes.
In the drawings, embodiments of the cassettes are shown as examples.
For the Type S cassette the dimensions are referred to three orthogonal Reference Planes X, Y, and 2 where
- The three datum areas A, B and C in the bottom surface of the case are in Plane Z
- Plane X is perpendicular to Plane Z and intersects the centres of datum holes A and B
- Plane Y is perpendicular to Plane X and Plane Z and intersects the centre of datum hole A.
For the Type L cassette the dimensions are referred to three orthogonal Reference Planes X, Y, and Z where
- The three datum areas E, F and G in the bottom surface of the case are in Plane Z
- Plane X is perpendicular to Plane Z and intersects the centres of datum holes E and F
- Plane Y is perpendicular to Plane X and Plane Z and intersects the centre of datum hole E.
Figures 1 to 19 and sub-cl ause 8.2 define the dimensions of the case and reels for a Type S cassette.
Figures 20 to 39 and sub-clause 8.3 define the dimensions of the case and reels for a Type L cassette.
82 . Type S cassette
Figure 1 is a perspective view seen from the top.
Figure 2 is a perspective view seen from the bottom.
Figure 3 shows the top side with the lid closed using third angle projection.
Figure 4 shows the top side holding and label areas.
OISOLIEC
shows the bottom side with the lid removed.
Figure 5
Figure 6 shows the bottom side with the lid closed.
Figure 7 shows the details of the recognition holes.
Figure 8 shows the details of the write-inhibit plug.
shows the detail of the lid release insertion channel.
Figure 9
shows the lid unlock force direction.
Figure 10
Figure 11 shows the detail of the lid opening insertion channel.
Figure 12 shows the lid opening force direction.
Figure 13 shows the side view with the lid open.
Figure 14 shows the cassette reel.
shows the height of reels upon rotation.
Figure 15
Figure 16 shows the internal tape path.
Figure 17 shows the tape path to measure the extraction force.
Figure 18 shows the tape path to measure the friction torque of the take-up reel.
Figure 19 shows the tape access cavity requirements.
8.2.1 Overall dimensions (figure 3)
The overall dimensions of the case with the lid in the closed position are defined as follows. The total width of the case shall be
II = 96,0 mm t 0,3 mm
The total length of the case shall be
= 156,O mm ‘i( K
,-
The distance from the top of the case to the Reference Plane Z shall be
Z3 = 25,O mm t 0,3 mm
The front-top bevel edge shall start in the top surface at a distance
ZA = 3,0 mm t 0,5 mm from the front side and shall terminate in the front side at a distance
Z5 = 5,0 mm 2 0,5 mm from the top surface
The bottom-front edge of the case shall be rounded with a radius
rl = l,Omm+O,l mm
The distance from the rear side to plane X shall be
= 9,0 mm ‘+f z:
I6
The distance from the right side to plane Y shall be
= 8,0 mm $f :z
I,
,
8.2.2 Holding areas (figure 4)
The holding areas, shown cross-hatched, lie in Plane Z and shall be the areas along which the cassette shall be held down when
inserted into the drive. The left and right edge holding areas shall extend from the rear side a distance of
Is = 69,4 mm min.
The width of the holding surface along the rear edge shall be
Z9 = 10,2 mm min.
The width of the left and right holding surfaces shall be
ZiO = 5,7 mm min.
8.2.3 Window
A window may be provided on the top surface so that a part of the reels is visible. The window, if provided, shall not extend
beyond the height of the cassette and shall not extend beyond the inner edge of the holding areas.

OISOIIEC
8.2.4 Label areas (figure 4)
A portion of the rear side of the cassette and a portion of the top surface of the cassette may be used for labels. The position and
the size of the labels shall not interfere with the operation or clearance requirement of the cassette component parts. The area
used for labels on the top surface shall not extend beyond the inner edges of the holding areas.
The position and dimensions of the label area on the rear side are defined as follows.
The distance from the top of the case to the top of the label area, and from the bottom of the label area to Plane Z, shall be
1 11 = 3,0 mm t 0,3 mm
The distance from both the left and right sides of the case to the edges of the label area shall be
12 = 7,0 mm t 0,3 mm
The depth of the top surface label depression shall be 0,3 mm max.
The depth of the rear side label depression shall be 0,5 mm t 0,l mm.
8.2.5 Datum areas and datum holes (figures 5 and 6)
The annular datum areas A, B and C shall lie in plane Z and determine the vertical position of the cassette in the drive.
The annular datum area D shall be parallel to datum plane Z and within 0,3 mm of it.
Each datum area shall have a diameter di = 10,O mm + 0,l mm and be concentric with the respective datum hole.
The centres of datum holes A and B lie in plane X.
The centre of datum hole A shall be at the intersection of planes X and Y.
The distance from the centre of the datum hole B to plane Y shall be
i3 = 140,O mm t 0,3 mm
The distance from the centre of the datum hole C to plane Y shall be
1 14 = 120,O mm t 0,3 mm
The distance from the centre of the datum hole D to plane Y shall be
Z15 = 20,O mm t 0,2 mm
The distance from the centre of the datum holes C and D to plane X shall be
I 16 = 740 mm k 0,2 mm
The diameter of datum holes A and D shall be
1 17 = 5,5 mm ~~$~~ as shown in section C-C of figure 6
.
The depth of all four datum holes shall be
1 19 = 9 mm min.
The distance across the flats of datum holes B and C shall be 117
The distance of the elongation in datum holes B and C shall be
1 18 = 8,00 mm t 0,15 mm as shown in section E-E of figure 6.
8.2.6 Support areas (figure 5)
The cassette support areas are shown cross-hatched, in figure 5. Support areas A, B, C and D shall be coplanar with datum area
A, B, C and D, respectively, within k 0,05 mm.
The areas within 1 mm of the edge of the cassette shall not be included in the support areas and shall be recessed from the
support areas.
The dimensions and position of the support areas shall be defined as follows.
The support area surrounding datum hole A shall be defined by
OISO/IEC
120 = 9,0 mm t 0,2 mm
1-21 = 20,O mm t 0,2 mm
Z2* = 10,OO mm t 0,15 mm
Zz3 = 0,4 mm t 0,2 mm
The support area surrounding datum hole B shall be defined by ZzO Zzl and
,
I 24 = 130,O mm t 0,3 mm
t 0,3 mm
1 35 = 140,4 mm
de
The support area surrounding datum hole D shall be defined by
126 = 62,0 mm 2 0,2 mm
Z2, = 72,3 mm t 0,3 mm
Z28 = 80,O mm t 0,3 mm
1 29 = 85,O mm t 0,3 mm
Z30 = 10,OO mm t, 0,15 mm
1 31 = 40,O mm t 0,2 mm
The support area surrounding datum hole C shall be defined by Z26, Z2*, 229 and
1 _32 = 68,0 mm ‘~$~~
mm
1 33 = 100,O mm t 0,3
1 34 = 130,O mm t, 0,3 mm
8.2.7 Guiding grooves (figure 3 and 6)
The cassette shall be provided with four guiding grooves for correct insertion into the drive.
The distance from Plane X to the rear edge of the guiding groove on the top surface shall be
/35=2,5mmIr0,1 mm
The width of top and bottom guiding grooves shall be
Z36 = 3,0 mm 2 0,l mm
The distance across the flanged opening at the left and right edges of both the top and bottom guiding grooves shall be
137 = 6,0 mm t 0,3 mm
The depth of the top and bottom guiding grooves shall be
Z3s = 1,4 mm min.
The distance from Plane Z to the bottom edge of the right side guiding groove shall be
1 = 11 ,OO mm ‘i$ ::
The width of right and left side guiding grooves shall be
1 4. = 3,0 mm ‘,“;“,m,m
The distance from Plane Z to the bottom of the right side flanged opening at the front shall be
Z41 = 9,0 mm t 0,3 mm
The width of the flanged opening of the right and left guiding grooves at the front shall be
I 42 = 7,00 mm t 0,15 mm
The distance from the front along the right and left guiding grooves to the termination of the flanges shall be
Z43 = 8,OO mm t 0,15 mm
The depth of the left and right side guiding grooves shall be
Z44 = 1,l mm min.
The distance from Plane Z to the bottom of the left flanged opening at the front shall be
OISOIIEC ISO/IEC 15731:1998 (E)
L 45 = 14,00 mm ‘,“;h ”zf
1-
The distance from Plane Z to the bottom edge of the left side guiding groove shall be
Z46 = 12,0 mm t 0,3 mm
The distance from the top surface to the extent of chamfer in the bottom of the top guiding groove on the left and right sides
shall be
1 47 = 1,90 mm t 0,15 mm
The angle of the chamfer in the bottom of the top guiding groove at the left and right ends shall be
a1 =30"+3"
The angle of the flange opening of the top guiding groove at both ends shall be
a2 = 30” t 3”
Recognition holes (figure 6 and 7)
8.2.8
There shall be 7 recognition holes numbered 1 to 7.
The position and dimensions of the recognition holes 1 to 6 are as follows.
A line through and locating the centres of holes 6 and 1 shall be
1 4g = 70,00 mm k 0,15 mm from Plane Y
The centre of hole 6 shall be located
1 49 = 48,0 mm t 0,2 mm from Plane X
The centres of holes 4 and 5 shall be located
ZsO = 3,40 mm t 0,05 mm to the left and right of a line through the centres of holes 1 and 6
The location of a line through the centres of hole 4 and 5 shall be a distance
1 s1 = 3,6 mm t 0,l mm from the centre of hole 6
Recognition holes 2 and 3 are D shaped with the flats next to hole 1; the flats shall be a distance
1 57 = 4,00 mm t 0,05 mm from the centre of hole 1
-I
The distance of a line through the centres of holes 1,2 and 3 from Plane X shall be
Z53 = 56,0 mm t 0,2 mm
The length of the flat of holes 2 and 3 shall be
1 54 = 3,4 mm ‘,“$z
The distance from the centre to the flat of holes 2 and 3 shall be
1 55 = 1,7 mm +.gO$zz with radius Zss, located Zss from the flat.
Holes 1 and 3 contain a tab as shown in view Q of figure 6 in figure 7.
The distance from the tab surface to the bottom of the cavity behind the tab shall be
Zs6 = 10 mm min. as shown in section F-F in figure 7.
The depth of holes 4,5 and 6 shall be
Zs7 = 5 mm min. as shown in section G-G of figure 7
The radius of the D holes 2 and 3 shall be
r2 = 1,7 mm ‘,“frnT
The diameter of holes 1, 4, 5 and 6 shall be

OISOLIEC
= 3,4 mm ‘,“b$zz
d2
Recognition hole 7 is located in the bottom right side of the case shown in view P of figure 6 in figure 7.
The distance from Plane Y to the surface of hole 7 nearest to the right edge of the case shall be
Zs8 = 5,s mm t 0,2 mm
The distance from Plane Y to the surface of hole 7 farthest from the right edge of the case shall be
1 59 = 1,6 mm t 0,l mm
The distance from Plane X to the surface of hole 7 nearest to the rear edge of the case shall be
1 6O = 50,0 mm ‘,“; ‘zG
The distance from Plane X to the surface of hole 7 farthest from the rear edge of the case shall be
1 61 =57,00 mm ‘,“firny
The surfaces on the case bottom and right side surrounding recognition hole 7 are slightly recessed.
The distance from Plane Y to the edge of the recessed area farthest from the right edge shall be
Zh2 = 0,4 mm t 0,2 mm
The distance from Plane X to the nearest edge of the recessed area along the right edge of the case shall be
1 63 = 46,0 mm t 0,5 mm
The extent of the recessed area along the right edge of the case shall be
ZH = 15,O mm t 0,5 mm
The inside corners of the recognition hole 7 farthest from the right edge of the case shall have fillets defined by
Zhs = 1,O mm ~fr 0,2 mm as shown in view P of figure 7.
The depth of the recess below the bottom and right side surfaces shall be
Z66 = 0,5 mm max.
The depth of recognition hole 7 shall be
Ze7 = 10 mm min.
This International Standard prescribes the following states of these recognition holes.
- Recognition hole 1 shall be closed.
- Recognition hole 2 shall be open.
- Recognition hole 3 shall be closed.
- Recognition hole 4 shall be open.
- Recognition hole 5 shall be open.
- Recognition hole 6 shall be open.
- Recognition hole 7 shall be open.
Tabs may be used to close the recognition holes. The dimensions of the tabs, if used, shall be as defined in the section F-F of
figure 7. The tabs shall withstand an applied force of 2,0 N max. without being punched out.
The surface of the tabs shall be recessed from the bottom surface a distance
Z68 = 0,3 mm max.
The space around the knockout tab in recognition holes 1 and 3, as viewed in section F-F of figure 7, shall be
ZG9 = 0,7 mm max.
8.2.9 Write-inhibit plug (figure 8)
The write-inhibit plug is located on the left side at the bottom of the case as shown in figure 6, view R.
OISO/IEC ISO/IEC 15731:1998 (E)
The distance in Plane Z from Plane X to the near edge of the write-inhibit plug hole shall be
Z70 = 52,5 mm t 0,2 mm
The span of the write-inhibit plug hole shall be
1 71 = 7,00 mm ‘,“iilf as shown in view R of figure 8.
The distance on the left side of the case from Plane X to the near edge of the slider opening shall be
172 = 52,8 mm min.
The distance on the left side of the case from Plane X to the far edge of the slider opening shall be
l- 73 = 58,8 mm max.
The distance in Plane Z from Plane Y to the inner side of the write-inhibit plug hole shall be
1 74 = 141,60 mm t 0,15 mm
The distance from the inner side of the write inhibit hole to the slide rail shoulder shall be
1 75 = 5,OO mm Ttii, “,”
The distance on the left side from Plane Z to the far edge of the write-inhibit plug detent hole shall be
I 76 = 9,4 mm max.
the body of the write-inhibit plug shall extend
The tang on the left side of
Z77 = 1,7 mm max.
The surface of the write-inhibit plug, when in the write-enable position, shall be recessed from Plane Z a distance
Z78 = 0,5 mm max.
When the write-inhibit plug is pushed down, recording on the tape is inhibited.
The distance from Plane Z to the surface of the plug in the write-inhibit position shall be
1 79 = 4,5 mm min.
The write-inhibit plug shall not be deformed by 0,3 mm or more when a force of 2,0 N is applied to the centre of it. The force
required to push down or lift up the write-inhibit plug shall be less than 40 N.
8.2.10 Pre-positioning surface (figures 3 and 5)
The pre-positioning surfaces are parallel to Plane Y in the front of the bottom surface and determine the initial location of the
cassette as it is inserted into the drive loading slot.
The distance of the right side pre-position surface from Plane Y shall be
280 = 1,2 mm t 0,4 mm as shown in figure 5
The distance of the left side pre-position surface from Plane Y shall be
Z8* = 137,7 mm t 0,5 mm
The height of the pre-position surfaces above Plane Z shall be
Zg2 = 3,0 mm t 0,l mm as shown in figure 3
ZsJ = 87,0 mm . ‘,“; ‘,m,m
The distance from Plane X to the front of the left and right pre-position surfaces shall be
_
8.2.11 Cassette lid (figures 9,10,11,12 and 13)
The cassette shall include a lid for protection of the tape during handling, storage and transportation. The lid shall be
automatically locked when the lid is closed and it shall be unlocked when the release pin in the drive is inserted into the channel
shown in figure 9.
The distance from Plane X to the near edge of the lid release insertion channel shall be I,, = 75,O mm : ‘,“frny
>
ISO/IEC X731:1998 (E) OISO/IEC
The distance from Plane Y to the far wall of the lid release insertion channel shall be
18s = 141,8 mm min.
The distance from Plane 2 to the near wall of the cavity containing the locking mechanism shall be
1 86 = 2,4 mm max.
The distance from Plane 2 to the far wall of the cavity containing the locking mechanism shall be
lg7 = 585 mm min.
The design of the locking mechanism is not specified by this International Standard except that it shall be operated by the
release pin in the drive. The lid release mechanism shall be actuated when the drive release pin is in the cross-hatched area
shown in section J-J and defined by 187 and
lg8 = 74,2 mm max.
1 89 = 758 mm min.
19() = 3 mm max.
The force needed to unlock the lid shall be less than 1 N in the direction shown by figure 10.
After the lid is unlocked, the lid shall be open when the lid opening lever in the drive is inserted into the channel shown in
figure 11.
The distance from Plane X to the near end of the lid opening channel shall be
191 = 77,3 mm max.
The distance from Plane Y to the relief edge in the front bottom lid surface shall be
192 = 2,4 mm max.
The distance from Plane Y to the right inside wall of the lid shall be
lg3 = 5 mm min.
The distance from bottom surface of the case to the front bottom edge of the lid shall be
1 94 = 0,l mm * 0,l mm
The bottom front edge of the lid shall have a flat for the distance defined by
195= 1,2mm+0,2mm
The inside corner of the lid shall be rounded with a radius
r3 = 1,0 mm t 0,l mm
The inside front bottom edge of the lid shall be chamfered at an angle defined by
a3 = 30” t 3” starting at the flat defined by 19s
The force needed to open the lid shall be 1,5 N max. in the direction shown in figure 12.
The lid rotates around an axis defined in figure 13 by dimensions
196 = 69,0 mm t 0,5 mm and
197 = 18,0 mm * 0,5 mm
The maximum possible lid opening distance shall be
1 98 = 29 mm min.
Cassette reel lock (figure 13)
8.2.12
The reels shall be locked when the cassette is removed from the tape drive and shall be unlocked when the cassette is inserted
into the drive.
The desi gn of the locking mechanism is not spec ified by this International Stan dard except that the reel shall be completely
released when the cassette lid is opened a distance from reference plane Z defined
bY
199 = 23,5 mm max. The minimum distance required to unlock the reels is not specified.
OISOIIEC ISO/IEC 15731:1998 (E)
8.2.13 Reel access holes (figure 6)
The case shall have two circular reel access holes in the bottom of the case which shall allow penetration of the drive spindles.
The centreline of both reel holes shall be the distance from Plane X defined by
1 loo=31,0mm~0,2mm
The distance from Plane Y along the line defined by lloo to the centre of the right reel hole shall be
1 1o1 = 32,0 mm t, 0,2 mm
The distance from Plane Y along the line defined by lloo to the centre of the left reel hole shall be
1 1o2 = 108,O mm + 0,2 mm
The diameter of both reel holes shall be
d3 = 33 mm min.
8.2.14 Reels (figure 14)
The reels have a spindle-receiving cavity extending from the bottom surface, with inward facing gear teeth for transferring
drive, and a round upper cylinder to define the axis of rotation precisely.
The diameter of the round upper cylinder in the receiving cavity shall be
= 11,OO mm ~~&j~~
d4
The tops of the inside gear teeth shall lie in a cylinder suface with a diameter defined by
= 14,0 mm ‘$!E
4 ,-
The base of the inside gear teeth shall lie in a cylinder suface with a diameter defined by
de = 18,0 mm t 0,2 mm
The base surface of the reel is formed by an annular ring with an inside diameter that shall be
d7 = 27,6 mm t 0,2 mm and an outside diameter that shall be
d8 = 30,O mm t 0,2 mm
The width of the tops of the inside gear teeth shall be
1 1o3 = 2,0 mm t 0,5 mm
The distance from the reel base annular ring to the inside lower flange at the tape hub surface shall be
1 1o4 = 3,75 mm : ‘,“; ‘,“:I
The distance between the lower and upper flanges at the tape hub surface shall be
1 = 13,5 mm ‘,“; ‘E
,
The distance from the reel base annular ring to the top of the inside gear teeth base cylinder shall be
lIo6 = 9,00 mm t 0,15 mm
The distance from the reel base annular ring to the start of the round upp
...