ISO/IEC 15895:1999

INTERNATIONAL ISO/IEC
STANDARD 15895
First edition
1999-12-15
Information technology — Data
interchange on 12,7 mm 128-track
magnetic tape cartridges — DLT 3-XT
format
Technologies de l'information — Échange de données sur cartouches
de bande magnétique de 12,7 mm, 128 pistes — Format DLT 3-XT
Reference number
©
ISO/IEC 1999
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ii © ISO/IEC 1999 – All rights reserved

ISO/IEC
4.30 Test Recording Current 3
4.31 Typical Field 3
5 Conventions and notations 3
5.1 Representation of numbers 3
5.2 Dimensions 3
5.3 Names 3
5.4 Acronyms 3
6 Environment and safety 3
6.1 Cartridge and tape testing environment 4
6.2 Cartridge operating environment 4
6.3 Cartridge storage environment 4
6.4 Safety 4
6.4.1 Safeness 4
6.4.2 Flammability 4
6.5 Transportation 4
Section 2 - Requirements for the unrecorded tape 5
7 Mechanical and electrical requirements 5
7.1 Material 5
7.2 Tape length 5
7.3 Width 5
7.4 Total thickness 5
7.5 Discontinuity 5
7.6 Longitudinal curvature 5
7.6.1 Requirement 5
7.6.2 Procedure 5
7.7 Out-of-Plane distortions 5
7.8 Cupping 5
7.9 Roughness of the coating surfaces 5
7.9.1 Roughness of the back coating surface 5
7.9.2 Roughness of the magnetic coating surface 5
7.10 Coating adhesion 6
7.11 Layer-to-layer adhesion 6
7.11.1 Requirements 6
7.11.2 Procedure 6
7.12 Modulus of elasticity 7
7.12.1 Requirement 7
7.12.2 Procedure 7
7.13 Flexural rigidity 7
7.13.1 Requirement 7
7.13.2 Procedure 8
7.14 Tensile yield force 8
7.14.1 Procedure 8
7.15 Electrical resistance 8
7.16.1 Requirement 8
7.15.2 Procedure 8
7.16 Inhibitor tape 9
7.17 Abrasivity 9
7.17.1 Requirement 9
7.17.2 Procedure 9
7.18 Light transmittance of the tape and the leader 9
7.19 Coefficient of dynamic friction 9
7.19.1 Requirements 9
7.19.2 Procedure for the measurement of the friction between the magnetic surface and the back surface 10
iv
ISO/IEC ISO/IEC 15895:1999 (E)
7.19.3 Procedure for the measurement of the friction between the magnetic surface or the back surface and calcium
titanate ceramic 10
8 Magnetic recording characteristics 10
8.1 Typical Field 11
8.2 Signal amplitude 11
8.3 Resolution 11
8.4 Overwrite 11
8.4.1 Requirement 11
8.5 Peak shift 11
8.5.1 Requirement 11
8.5.2 Procedure 11
9 Tape quality 12
9.1 Missing pulses 12
9.1.1 Requirement 12
9.2 Missing pulse zone 12
9.2.1 Requirement 12
9.3 Tape durability 12
Section 3 - Mechanical specifications of the tape cartridge 12
10 General 12
10.1 Bottom side and right side 13
10.2 Back side and left side 14
10.3 Tape reel 14
10.4 Tape leader and markers 15
10.5 Front side 16
10.6 Operation of the cartridge 16
10.7 Tape winding 17
10.8 Moment of inertia 17
10.9 Material 17
11 Method of recording 26
11.1 Physical recording density 26
11.2 Channel bit cell length 26
11.2.1 Average Channel bit cell length 26
11.2.2 Long-term average Channel bit cell length 26
11.2.3 Short-term average Channel bit cell length 26
11.3 Flux transition spacing 26
11.4 Read signal amplitude 26
11.5 Azimuth 27
11.6 Channel skew 27
12 Tape format 27
12.1 Reference Edge 27
12.2 Direction of recording 27
12.3 Tape layout 27
12.4 Calibration and Directory Area 27
12.4.1 Scratch Area 28
12.4.2 Guard Area G1 28
12.4.3 Calibration Tracks Area 28
12.4.4 Guard Area G2 29
12.4.5 Directory Area 29
12.4.6 Guard Area G3 29
12.5 Data Area 29
12.5.1 Physical tracks 30
12.5.2 Width of the physical tracks 30
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ISO/IEC
12.5.3 Logical tracks 30
12.5.4 Locations of the physical tracks 30
12.5.5 Layout of tracks in the Data Area 31
13 Data format 31
13.1 Data Bytes 32
13.2 Logical Blocks 32
13.3 Data Blocks 32
13.4 Types of Logical Blocks 32
13.5 Entities 32
13.6 Logical Block format 32
13.6.1 Preamble 33
13.6.2 Sync 33
13.6.3 Data Field 33
13.6.4 EDC 35
13.6.5 Control Field 1 (CF1) 35
13.6.6 Control Field 2 (CF2) 36
13.6.7 CRC 37
13.6.8 Postamble 37
14 Use of Logical Blocks 37
14.1 Data Blocks 37
14.2 Filler Blocks 37
14.3 End of Track Blocks (EOTR) 38
14.4 End of Data Blocks (EOD) 38
14.5 ECC Blocks 38
15 Format of Entities 38
16 Error handling 38
Annexes
A - Measurement of light transmittance 39
B - Generation of the Data Block CRCs 42
C - ECC generation 43
D - Generation of page CRCs 46
E - Format of MAP entries 47
F - Format of Control Field 1 48
G - Format of Control Field 2 49
H - Recommendations for transportation 50
J - Inhibitor tape 51
K - Recommendations on tape durability 52
L - Handling guidelines 53
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ISO/IEC ISO/IEC 15895:1999 (E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission)
form the specialized system for worldwide standardization. National bodies that are members of ISO 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. ISO and IEC technical committees
collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in
liaison with ISO and IEC, also take part in the work.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
In the field of information technology, ISO 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.
Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of
patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
International Standard ISO/IEC 15895 was prepared by ECMA — European association for standardizing
information and communication systems (as ECMA-258) 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 ISO and IEC.
Annexes A to G form a normative part of this International Standard. Annexes H to L are for information only.
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ISO/IEC
Introduction
This International Standard constitutes a further development of the magnetic tape cartridge specified in International Standard
ISO/IEC 14833. A higher capacity is achieved by using a thinner, thus longer tape.
viii
4 Definitions
For the purposes of this International Standard, the following definitions apply.
4.1 Average Signal Amplitude: The average peak-to-peak value of the output signal from the read head at the
physical recording density of 1 640 ftpmm measured over a minimum length of track of 25,4 mm, exclusive of missing pulses.
4.2 azimuth: The angular deviation, in degrees of arc, of the mean flux transition line of the recording made on a track
from the line normal to the Reference Edge.
4.3 back surface: The surface of the tape opposite the magnetic coating which is used to record data.
4.4 Beginning-Of-Tape markers (BOT 1 and BOT 2): Two holes punched on the centreline of the tape towards
the end nearest to the leader.
4.5 byte: An ordered set of bits acted upon as a unit.
Note - In this International Standard, all bytes are 8-bit bytes.
4.6 cartridge: A case containing a single supply reel of 12,7 mm wide magnetic tape with a leader attached at the
outer end.
4.7 Cyclic Redundancy Check (CRC) character: A 64-bit character, generated by a mathematical computation,
used for error detection.
4.8 Early Warning (EW): A signal generated by the drive indicating the approaching end of the recording area.
4.9 Error-Detecting Code (EDC): A mathematical computation yielding check bytes used for error detection.
4.10 End-Of-Tape marker (EOT): A hole punched on the centreline of the tape towards the end farthest from the
leader.
4.11 Entity: A group of twenty physical blocks treated as a logical unit and recorded on a logical track.
4.12 Error-Correcting Code (ECC): A mathematical computation yielding check bytes used for the correction of
errors detected by the CRC and the EDC.
4.13 flux transition position: The point which exhibits the maximum free-space flux density normal to the tape
surface.
4.14 flux transition spacing: The distance on the magnetic tape between successive flux transitions.
4.15 Logical Block: The two physical blocks simultaneously written on, or read from, the two physical tracks of a
logical track.
4.16 logical track: A pair of physical tracks that are written or read simultaneously.
4.17 magnetic tape: A tape that accepts and retains magnetic signals intended for input, output, and storage purposes
on computers and associated equipment.
4.18 Master Standard Reference Tape: A tape selected as the standard for reference field, signal amplitude,
resolution, peakshift, and overwrite characteristics.
Note - The Master Standard Reference Tape is maintained by the Quantum Corporation.
4.19 object: A Record or a Tape Mark Block.
4.20 page: A logical division of a physical block.
4.21 physical block: A set of contiguous bytes recorded on a physical track and considered as a unit.
4.22 physical recording density:
The number of recorded flux transitions per unit length of track, expressed in flux
transitions per millimetre (ftpmm).
4.23 physical track: A longitudinal area on the tape along which a series of magnetic signals can be recorded.
4.24 Record: A collection of User Bytes, the number of which is determined by the host.
4.25 Reference Edge: The bottom edge of the tape when viewing the magnetic coating of the tape with the BOT holes
to the left and the EOT hole to the right of the observer.
4.26 Reference Field: The Typical Field of the Master Standard Reference Tape.
4.27 Secondary Standard Reference Tape: A tape the characteristics of which are known and stated in relation to
those of the Master Standard Reference Tape.
ISO/IEC  ISO/IEC 15895:1999 (E)
Note - Secondary Standard Reference Tapes can be ordered under Reference "SSRT/DLT3XT" until the year 2003 from Quantum Corporation, 333 South
Street, Shrewsbury, Mass. 01545-4195, USA. It is intended that these be used for calibrating tertiary reference tapes for routine calibration.
In principle, these Secondary Standard Reference Tapes will be available for a period of 10 years from the publication of the first version of this International
Standard. However, this period may be changed to take into account the demand for such Secondary Standard Reference Tapes.
4.28 Standard Reference Amplitude (SRA): The Average Signal Amplitude from the Master Standard Reference
Tape when it is recorded with the Test Recording Current at 1 640 ftpmm.
4.29 Standard Reference Current: The current that produces the Reference Field.
4.30 Test Recording Current: The current that is 1,1 times the Standard Reference Current.
4.31 Typical Field: In the plot of the Average Signal Amplitude against the recording field at the physical recording
density of 1 640 ftpmm, the minimum field that causes an Average Signal Amplitude equal to 95 % of the maximum Average
Signal Amplitude.
5 Conventions and notations
5.1 Representation of numbers
The following conventions and notations apply in this International Standard, unless otherwise stated.
− In each block and in each field the bytes shall be arranged with Byte 1, the least significant, first. Within each byte the bits
shall be arranged with Bit 1, the least significant, first and Bit 8, the most significant bit, last. This order applies to the data,
and to the input and output of the error-detecting and error-correcting codes, and to the cyclic redundancy characters.
− Letters and digits in parentheses represent numbers in hexadecimal notation.
− The setting of bits is denoted by ZERO or ONE.
− Numbers in binary notation and bit patterns are represented by strings of ZEROs and ONEs shown with the most significant

bit to the left.
5.2 Dimensions
The dimensions in figures 1 to 4 are nominal dimensions. Unless otherwise stated, all dimensions in figures 8 to 23 are in
millimetres with a tolerance of ± 50 mm.
5.3 Names
The names of basic elements, e.g. specific fields, are written with a capital initial letter.
5.4 Acronyms
BOT 1 Beginning of Tape No. 1
BOT 2 Beginning of Tape No. 2
CF1 Control Field 1
CF2 Control Field 2
CRC Cyclic Redundancy Check (character)
ECC Error-Correcting Code
EDC Error-Detecting Code
EOD End of Data
EOT End of Tape
EOTR End of Track
EW Early Warning
FCT1 Forward Calibration Track 1
FCT2 Forward Calibration Track 2
RCT1 Reverse Calibration Track 1
RCT2 Reverse Calibration Track 2
RLL Run Length Limited
SRA Standard Reference Amplitude
6 Environment and safety
Unless otherwise stated, the conditions specified below refer to the ambient conditions in the test or computer room and not to
those within the tape drive.
6.1 Cartridge and tape testing environment
...