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
Current Stage
9093 - International Standard confirmed
Start Date
20-Nov-2003
Completion Date
21-Aug-2020
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ISO/IEC 15731:1998 - Information technology -- 12,65 mm wide magnetic tape cassette for information interchange -- Helical scan recording -- DTF-1 format
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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)
---------------------- Page: 1 ----------------------
ISO/IEC 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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ISO/IEC 15731:1998 (E)
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
. . .
111
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0 ISO/IEC
ISO/IEC 15731:1998 (E)
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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ISO/IEC 15731:1998 (E)
0 ISO/IEC
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
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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0 ISO/IEC
ISO/IEC 15731:1998 (E)
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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0 ISO/IEC
ISO/IEC 15731:1998 (E)
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
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ISO/IEC 15731:1998 (E) 0 ISO/IEC
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
---------------------- Page: 8 ----------------------
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).

---------------------- Page: 9 ----------------------
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

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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
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OISO/IEC
ISO/IEC 15731:1998 (E)
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.
---------------------- Page: 12 ----------------------
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.
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OISOLIEC
ISO/IEC 15731:1998 (E)
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:
The distance from the right side to plane Y shall be
= 8,0 mm $f :z
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.

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OISOIIEC
ISO/IEC 15731:1998 (E)
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
...

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