ISO/IEC 1001:2012

INTERNATIONAL ISO/IEC
STANDARD 1001
First edition
2012-08-01
Information technology — File structure
and labelling of magnetic tapes for
information interchange
Technologies de l'information — Structure des fichiers et étiquetage des
bandes magnétiques pour l'échange d'information

Reference number
©
ISO/IEC 2012
©  ISO/IEC 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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ii © ISO/IEC 2012 – All rights reserved

Contents Page
Foreword . v
1  Scope . 1
2  Conformance . 1
2.1  Conformance of a magnetic tape volume set . 1
2.2  Conformance of an information processing system . 1
3  Normative references . 2
4  Terms and definitions . 2
5  Notation . 4
6  Arrangement of labels and files . 4
6.1  Arrangement of data on a volume . 4
6.2  Arrangement of label groups . 4
6.2.1  Labels . 4
6.2.2  Label sets . 5
6.2.3  Label groups . 5
6.3  Arrangement of file sections . 5
6.3.1  File section . 5
6.3.2  Labelled-Sequence . 5
6.4  Relationship of file sections to a volume. 6
6.5  Arrangement of files and file sets . 6
6.5.1  Files. 6
6.5.2  File sets . 6
6.6  Structure of a volume set . 7
7  File structure for data interchange . 7
7.1  File structure for data interchange for a-characters . 7
7.1.1  Blocks . 7
7.1.2  Records . 8
7.1.3  Files. 9
7.2  File structure for data interchange for e-characters . 10
7.2.1  Blocks . 10
7.2.2  Records . 10
7.2.3  Files. 11
8  Format and contents of the labels and label sets . 11
8.1  Format and contents of the labels and label sets for a-characters . 11
8.1.1  Character set and coding . 11
8.1.2  Justification of characters . 12
8.1.3  Volume Header Label Set (VOL1 to VOL9) . 12
8.1.4  Installation Volume Label Set (UVL1 to UVL9) . 14
8.1.5  File Header Label Set (HDR1 to HDR9) . 15
8.1.6  User File Header Label Set (UHL) . 20
8.1.7  End of Volume Label Set (EOV1 to EOV9) . 20
8.1.8  End of File Label Set (EOF1 to EOF9) . 23
8.1.9  User File Trailer Label Set (UTL) . 25
8.2  Format and contents of the labels and label sets for e-characters . 26
8.2.1  Character set and coding . 26
8.2.2  Justification of characters . 26
8.2.3  Volume Header Label Set (VOL1) . 26
8.2.4  File Header Label Set (HDR1 to HDR2) . 28
8.2.5  User File Header Label Set (UHL1 to UHL8) . 31
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8.2.6  End of Volume Label Set (EOV1 to EOV2) .32
8.2.7  End of File Label Set (EOF1 to EOF2) .33
8.2.8  User File Trailer Label Set (UTL1 to UTL8) .35
9  Levels of interchange (only a-characters) .36
9.1  Level 1 .36
9.2  Level 2 .36
9.3  Level 3 .36
9.4  Level 4 .36
10  Requirements for the description of systems .36
11  Requirements for an originating system .37
11.1  Requirements for an originating system for a-characters .37
11.1.1  General .37
11.1.2  Files .37
11.1.3  Labels .37
11.1.4  Restrictions .39
11.2  Requirements for an originating system for e-characters .39
11.2.1  General .39
11.2.2  Files .39
11.2.3  Labels .39
12  Requirements for a receiving system .40
12.1  Requirements for a receiving system for a-characters .40
12.1.1  General .40
12.1.2  Files .41
12.1.3  Labels .41
12.1.4  Restrictions .42
12.2  Requirements for a receiving system for e-characters .42
12.2.1  General .42
12.2.2  Files .43
12.2.3  Labels .43
Annex A (informative) Code tables for a-characters .45
A.1  a-characters .45
Annex B (normative) Code Tables for e-characters .46
B.1  e-characters .46
Annex C (informative) Initialized volumes .47
C.1  Purpose .47
C.2  Specification .47

iv © ISO/IEC 2012 – All rights reserved

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. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. 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 document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.
ISO/IEC 1001 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 23, Digitally Recorded Media for Information Interchange and Storage.
This first edition of ISO/IEC 1001 cancels and replaces the second edition of ISO 1001:1986, which has been
technically revised.
© ISO/IEC 2012 – All rights reserved v

INTERNATIONAL STANDARD ISO/IEC 1001:2012(E)

Information technology — File structure and labelling of
magnetic tapes for information interchange
1 Scope
This International Standard specifies the file structure and the labelling of magnetic tapes for the interchange
of information between users of information processing systems.
This International Standard also specifies
 volume and file structure;
 basic characteristics of the blocks containing the records constituting the file;
 recorded labels for identifying files, file sections and volumes of magnetic tapes;
 four nested levels of interchange.
Furthermore, this International Standard specifies requirements for the processes which are provided within
information processing systems, to enable information to be interchanged between different systems, utilizing
recorded magnetic tape as the medium of interchange. For this purpose it specifies the functions to be
provided within systems which are intended to originate or receive magnetic tape volumes which conform to
this International Standard.
2 Conformance
2.1 Conformance of a magnetic tape volume set
A magnetic tape volume set conforms to this International Standard when all information recorded on it
conforms to the specifications of this International Standard. A Statement of conformance shall identify the
lowest level of interchange to which the contents of the magnetic tapes conform.
A prerequisite to such conformance is conformance of each volume of the volume set to the same
International Standard for information interchange on magnetic tapes.
2.2 Conformance of an information processing system
An information processing system conforms to this International Standard if it meets all the requirements
specified in this International Standard either for an originating system, or for a receiving system, or for both
types of system. A statement of conformance shall identify which of these sets of requirements can be met by
the system.
© ISO/IEC 2012 – All rights reserved 1

3 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 646, Information technology — ISO 7-bit coded character set for information interchange
4 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
4.1
application program
program that processes the contents of records belonging to a file, and may also process selected attribute
data relating to the file or to the volume(s) on which it is recorded
NOTE An application program is a specific class of user as defined in this International Standard.
4.2
block
group of bytes recorded on a magnetic tape as a unit
4.3
blocked
attribute of records that indicates that they may begin at a byte that is not the first byte of a block
4.4
byte
string of eight binary digits operated upon as a unit
4.5
file
named collection of information consisting of zero or more records
4.6
file section
part of a file that is recorded on any one volume
4.7
file set
collection of one or more files recorded consecutively on a set of volumes
4.8
fixed-length record
record contained in a file in which all records must have the same length
4.9
implementation
set of processes within an information processing system which enable that system to behave as an
originating system, or as a receiving system, or as both types of system
4.10
Initialized volumes
magnetic tape already recorded in the first label group on the volume although no valid file sections are
recorded (See Annex C)
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4.11
installation
person or other entity which controls the use of one or more implementations which process and interchange
magnetic tapes
NOTE An installation is a specific class of user as defined in this International Standard.
4.12
label
record that identifies and characterizes a volume, or a file section on a volume
4.13
originating system
information processing system which can record a file set on a volume set for the purpose of data interchange
with another system
4.14
originator
person who is responsible for issuing commands to an originating system
4.15
receiving system
information processing system which can read a file set from a volume set which has been recorded by
another system for the purpose of data interchange
4.16
recipient
person who is responsible for issuing commands to a receiving system
4.17
record
related data treated as a unit of information
4.18
segmented record (only a-characters)
record contained in a file which is assigned to contain records that may have different lengths and that may be
recorded entirely in one block or over more than one block
4.19
International Standard for information interchange (only a-characters)
standard that specifies the recording method and the track format of a magnetic tape (for example ISO 1863)
4.20
Tape Mark
control block used as a delimiter
4.21
user
person or other entity that causes the invocation of the services provided by an implementation
4.22
variable-length record
record contained in a file in which the records may have different lengths
4.23
volume
dismountable reel of magnetic tape
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4.24
volume set
collection of one or more volumes, on which a file set is recorded
5 Notation
The following notation is used in this International Standard:
BP: Byte position within the label
L:  Length of the field in number of byte positions
a-character(s): Any of the allowed characters (see 8.1.1)
e-character(s): Any of the allowed characters (see 8.2.1)
Digit(s): Any digit from ZERO to NINE.
With the exception of SPACE, a group of capital letters in the content column of a table specifying label
contents indicates that these characters shall appear in the order given and in the corresponding byte
positions of the field specified, for example VOL in BP 1 to 3 of the Volume Header Labels. In the tables and
thoughout this International Standard, SPACE signifies the character coded in position 2/0 of ISO 646 or 4/0
of e-character(s).
6 Arrangement of labels and files
6.1 Arrangement of data on a volume
A volume shall be recorded with a sequence of blocks and Tape Marks. The sequence shall commence with a
block, and shall terminate within the usable recording area.
6.2 Arrangement of label groups
6.2.1 Labels
A label shall be a record that shall have a length of 80 bytes. Each label shall be recorded within the first or
only 80 byte positions of a block. If the block contains any additional bytes, they shall be recorded with any
desired bit combinations.
Each label shall be of one of the following types:
Volume Header
Installation Volume (only a-characters)
File Header
User File Header
End of File
End of Volume
User File Trailer
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6.2.2 Label sets
A sequence of one or more labels of the same type, recorded in consecutive blocks, shall be a label set of that
type. All labels in a set shall be numbered consecutively starting from 1, except those labels in the User File
Header and User File Trailer Label Sets.
6.2.3 Label groups
A label group shall consist of a mandatory label set, optionally followed by a second label set of a different
type. Each label group shall be of one of the types listed in Table 1, and shall include only those label sets
listed in the corresponding entry of the table. The first set listed in each table entry is the mandatory set, and
the second set listed is the optional set.
Table 1 — Label groups
Label group Label sets
Beginning of Volume Volume Header
Installation Volume (only a-characters)
Beginning of File Section File Header
User File Header
End of File Section End of Volume
User File Trailer
End of File End of File
User File Trailer
6.3 Arrangement of file sections
6.3.1 File section
A file section shall be recorded in a sequence of one or more blocks, or no blocks. If no blocks are recorded,
the file section is regarded as empty.
6.3.2 Labelled-Sequence
6.3.2.1
A Labelled-Sequence shall consist of the sequence of blocks and Tape Marks as listed below, recorded
consecutively:
a) Beginning of File Section Label Group;
b) Tape Mark;
c) a file section;
d) Tape Mark;
e) either an End of File Label Group or an End of File Section Label Group, as required in 6.3.2.2;
f) Tape Mark.
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6.3.2.2
If the file section is the last or only file section of a file, then the label group that follows it shall be an End of
File Label Group. Otherwise the label group shall be an End of File Section Label Group.
NOTE An End of File Section Label Group can only be the last label group on a volume because of the requirements
of 6.5.1.
6.3.2.3
Within a Labelled-Sequence the information contained in the File Header Label Set, and in the End of File or
End of Volume Label Set, shall apply to the file section that is recorded within the sequence.
6.3.2.4
Within a Labelled-Sequence the number of labels in an End of Volume or End of File Label Set shall be equal
to the number of labels in the File Header Label Set. Within all Labelled-Sequences in which the file sections
of a file are recorded, the number of File Header Labels shall be the same.
6.4 Relationship of file sections to a volume
The information on a volume shall consist of the sequence of blocks and Tape Marks as listed below,
recorded consecutively:
 Beginning of Volume Label Group;
 one or more Labelled-Sequences;
 Tape Mark.
Any recording following the last Tape Mark of the sequence shall be ignored in interchange.
The information that identifies and describes the volume shall be contained in the Volume Header Label Set,
within the Beginning of Volume Label Group.
6.5 Arrangement of files and file sets
6.5.1 Files
If a file is recorded entirely within one volume it shall consist of only one file section.
If a file is recorded over more than one volume, then only one file section of the file shall be recorded on any
one volume, and
 the first file section shall be recorded as the last or only file section on a volume;
 any intermediate file section shall be recorded as the only file section on a volume;
 the last file section shall be recorded as the first or only file section on a volume.
All sections of a file shall be numbered consecutively starting from 1.
6.5.2 File sets
A file set shall consist of one or more files having a common file set identifier. All files in a file set shall be
numbered consecutively starting from 1.
The files in a file set shall be recorded consecutively over a set of one or more volumes.
6 © ISO/IEC 2012 – All rights reserved

6.6 Structure of a volume set
A volume set shall be the set of volumes on which a file set is recorded. The volume set shall contain only one
file set.
7 File structure for data interchange
This clause specifies the file structure for data interchange in terms of data blocks and data records, and
identifies the label fields defined for that purpose.
7.1 File structure for data interchange for a-characters
7.1.1 Blocks
7.1.1.1 Characteristics
A block in which part of a file section is recorded shall contain one or more Measured Data Units (MDU). Each
MDU shall either be a fixed-length record, or shall contain a variable-length record or a record segment.
A block in which part of a file section is recorded may contain
 an Offset field preceding the first or only MDU;
 a Padding field following the last or only MDU.
The first or only MDU in a block shall begin at the first byte of the block after the Offset field (if any). Each
subsequent MDU shall begin at the byte immediately following the last byte of the preceding MDU in that
block. Each MDU shall end in the block in which it begins.
7.1.1.2 Block length
The length of a block shall be the number of bytes in the block. Within a file, all blocks may have different
lengths. The length of a block shall be the sum of
 the lengths of the MDUs in the block;
 the length of the Offset field;
 the length of the Padding field.
A maximum block length shall be assigned for a file. The block length shall not exceed the maximum value
specified by the relevant International Standard for information interchange.
7.1.1.3 Offset field
This field shall consist of not more than 99 bytes. It shall be reserved for implementation use. Its contents are
not specified by this International Standard and may be ignored in interchange.
7.1.1.4 Padding field
This field shall consist of a number of bytes sufficient to extend the length of a block either
a) to the minimum length required by the relevant International Standard for information interchange, or
b) to a greater length as required by the implementation.
© ISO/IEC 2012 – All rights reserved 7

Each byte of this field shall contain bit combination b to b = 0101 1110. This field shall be ignored in
8 1
interchange.
7.1.2 Records
7.1.2.1 Characteristics
A record shall have the following characteristics:
a) A record may be either a fixed-length record, or a variable-length record, or a segmented record.
b) A fixed-length record or a variable-length record shall be recorded entirely within one block; a segmented
record may be recorded in a part of one or more blocks.
c) The length of a record shall be the number of bytes in the record.
7.1.2.2 Fixed-length records
A fixed-length record shall be a record contained in a file that is assigned to contain only records of the same
length. The minimum assigned length of a fixed-length record shall be one byte and the maximum assigned
length shall not exceed the assigned block length less the length of the offset field. At least one byte of a
fixed-length record shall not contain bit combination b to b = 0101 1110.
8 1
7.1.2.3 Variable-length records
A variable-length record shall be a record contained in a file that is assigned to contain records that may have
different lengths.
A variable-length record shall be contained in an MDU. The MDU shall consist of a Record Control Word
(RCW), followed immediately by the variable-length record. The RCW shall consist of four characters which
shall be coded in accordance with ISO 646 and shall express the sum of the lengths of the record and of the
RCW as a four-digit decimal number.
A maximum record length shall be assigned for a file. The length of any record in the file shall not exceed this
value. The assigned maximum record length shall not be zero and shall not exceed the assigned block length
less the length of the Offset field and less the length of the RCW.
The minimum length of a variable-length record shall be zero.
7.1.2.4 Segmented records
A segmented record shall be a record contained in a file that is assigned to contain records that may have
different lengths and that may be recorded entirely in one block or over more than one block.
That part of a segmented record that is recorded in one block is a record segment. There shall be only one
segment of the same record in a block.
Successive segments of the same record within the same file sections shall be recorded in successive blocks.
Different segments of the same record shall only be recorded in different file sections if one of the segments is
recorded in the last block of a file section, and the next segment of the record is recorded in the first block of
the next non-empty file section of that file.
A maximum record length shall be assigned for a file. The length of any record in the file shall not exceed this
assigned value. The assigned maximum record length shall not be zero.
NOTE The assigned maximum record length is unbounded in that this International Standard specifies no limit to the
number of record segments in a record.
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A record segment shall be contained in an MDU. The MDU shall consist of a Segment Control Word (SCW),
followed immediately by the record segment. The SCW shall consist of five characters which shall be coded in
accordance with ISO 646.
The first character of the SCW is called the Segment Indicator, This character shall have one of the values 0,
1, 2 or 3 with the following meaning:
0 shall mean that the record begins and ends in this record segment;
1 shall mean that the record begins but does not end in this record segment;
2 shall mean that the record neither begins nor ends in this record segment;
3 shall mean that the record ends but does not begin in this record segment.
The last four characters of the SCW shall express as a decimal number the sum of the lengths of the record
segment and of the SCW.
The length of a record segment shall not exceed the assigned block length less the length of the Offset field
and less the length of the SCW.
The minimum length of a record segment shall be zero.
7.1.2.5 Coded representation of data
This International Standard does not specify the coded representation of the contents of a record.
7.1.3 Files
7.1.3.1 Characteristics
A file shall contain either only fixed-length records or only variable-length records or only segmented records.
7.1.3.2 Consistency of file attributes between file sections
The following label fields in the File Header Label Set for each file section of the same file shall contain the
same characters:
 File Identifier (HDR1 BP 5 to 21)
 File Set Identifier (HDR1 BP 22 to 27)
 File Sequence Number (HDR1 BP 32 to 35)
 Generation Number (HDR1 BP 36 to 39)
 Generation Version Number (HDR1 BP 40 and 41)
 File Accessibility (HDR1 BP 54)
 Record Format (HDR2 BP 5)
 Block Length (HDR2 BP 6 to 10)
 Record Length (HDR2 BP 11 to 15)
 Offset Length (HDR2 BP 51 to 52)
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7.1.3.3 File organization
The file organization shall be sequential.
7.2 File structure for data interchange for e-characters
7.2.1 Blocks
7.2.1.1 Characteristics
A block in which part of a file section is recorded shall contain one or more Measured Data Units (MDU).
Each MDU shall either be a fixed-length record or a variable-length record.
If an MDU is a variable-length record, the blocks in a file section shall begin at a Block Descriptor Word
(BDW). Each BDW shall consist of two-byte binary digits indicating the block length, as well as two-byte
reserved data. Each byte of the reserved data shall contain bit combination b to b = 0000 0000.
8 1
The first or only MDU in a block shall begin at the first byte of the block. If there is a BDW, however, the MDU
shall begin at the byte immediately following the BDW. Each subsequent MDU shall begin at the byte
immediately following the last byte of the preceding MDU in that block. Each MDU shall end in the block in
which it begins.
7.2.1.2 Block length
The length of a block shall be the number of bytes in the block. Within a file, all blocks may have different
lengths. The length of a block shall be the sum of
 the lengths of the MDUs in the block;
 the length of the BDW for a variable-length record.
A maximum block length shall be assigned for a file. The maximum block length shall not exceed the
maximum value specified by the implementation.
If an MDU is a fixed-length record, the maximum block length shall be an integral multiple of the record length.
7.2.2 Records
7.2.2.1 Characteristics
A record shall have the following characteristics:
a) A record may be either a fixed-length record, or a variable-length record.
b) A record shall be recorded entirely within one block.
c) The length of a record shall be the number of bytes in the record.
7.2.2.2 Fixed-length records
The minimum length of a fixed-length record shall be one byte and the maximum length shall be the maximum
block length.
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7.2.2.3 Variable-length records
A variable-length record shall begin at a Record Descriptor Word (RDW). Each RDW shall consist of two-byte
binary digits indicating the sum of the lengths of the record contents and the RDW, as well as two-byte
reserved data. Each byte of the reserved data shall contain bit combination b8 to b1 = 0000 0000.
A maximum record length shall be assigned for a file. The length of any record in the file shall not exceed this
value. The assigned maximum record length shall not exceed the assigned maximum block length less the
length of the BDW.
7.2.2.4 Coded representation of data
This International Standard does not specify the coded representation of the contents of a record.
7.2.3 Files
7.2.3.1 Characteristics
A file shall contain either only fixed-length records or only variable-length records.
7.2.3.2 Consistency of file attributes between file sections
The following label fields in the File Header Label Set for each file section of the same file shall contain the
same characters:
 File Identifier (HDR1 BP 5 to 21)
 File Set Identifier (HDR1 BP 22 to 27)
 File Sequence Number (HDR1 BP 32 to 35)
 Record Format (HDR2 BP 5)
 Block Length (HDR2 BP 6 to 10)
 Record Length (HDR2 BP 11 to 15)
7.2.3.3 File organization
The file organization shall be sequential.
8 Format and contents of the labels and label sets
8.1 Format and contents of the labels and label sets for a-characters
8.1.1 Character set and coding
Unless otherwise stated, the characters in the labels shall be coded in accordance with ISO 646.
The 57 characters used in the labels shall be those in the following positions of the International Reference
Version (IRV)
2/0 to 2/2
2/5 to 2/15
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3/0 to 3/15
4/1 to 4/15
5/0 to 5/10
5/15
These 57 characters are referred to as “a-characters” (see annex A).
8.1.2 Justification of characters
In the label fields, characters shall be justified as follows:
 in each field, the contents of which are specified by this International Standard to be digits, the digits
shall be right-justified and any remaining positions on the left shall be filled with ZEROs;
 in each field, the contents of which are specified by this International Standard to be a-characters,
the a-characters shall be left-justified and any remaining positions on the right shall be filled with
SPACEs.
8.1.3 Volume Header Label Set (VOL1 to VOL9)
A Volume Header Label Set shall be a label set comprising at least one Volume Header Label and at most
nine such labels.
8.1.3.1 First Volume Header Label (VOL1)
The First Volume Header Label shall identify the volume, the owner, the accessibility conditions, the
implementation recording the Volume Header Label Set, and the version of this International Standard which
applies. (see Table 2)
Table 2 — First Volume Header Label (VOL1)
BP Field name L Content
1 to 3 Label Identifier 3 VOL
4 Label Number 1 1
5 to 10 Volume Identifier 6 a-characters
11 Volume Accessibility 1 a-character
12 to 24 (Reserved for future standardization) 13
SPACEs
25 to 37 Implementation Identifier 13 a-characters
38 to 51 Owner Identifier 14 a-characters
52 to 79 (Reserved for future standardization) 28 SPACEs
80 Label Standard Version 1 4
8.1.3.1.1 Fields reserved for future standardization (BP 12 to 24 and BP 52 to 79)
These fields shall be reserved for future standardization.
The characters in these fields shall be SPACEs.
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8.1.3.1.2 Label Identifier (BP 1 to 3)
This field shall specify the Label Identifier.
The characters in this field shall be VOL.
8.1.3.1.3 Label Number (BP 4)
This field shall specify the Label Number.
The Character in this field shall be the digit ONE.
8.1.3.1.4 Volume Identifier (BP 5 to 10)
This field shall specify an identification of the volume.
The characters in this field shall be a-characters.
8.1.3.1.5 Volume Accessibility (BP 11)
This field shall specify whether there are installation-specified restrictions under which the volume may be
accessed.
The character in this field shall be an a-character.
SPACE shall mean that no such restrictions for access to the volume have been agreed upon between the
originator and the recipient of the volume.
Any other a-character shall mean that there are particular restrictions for access to the volume, that are
subject to agreement between the originator and the recipient of the volume.
8.1.3.1.6 Implementation Identifier (BP 25 to 37)
This field shall specify an identification of the implementation which recorded the Volume Header Label Set.
The characters in this field shall be a-characters.
8.1.3.1.7 Owner Identifier (BP 38 to 51)
This field shall specify an identification of the owner of the volume.
The characters in this field shall be a-characters.
8.1.3.1.8 Label Standard Version (BP 80)
This field shall specify the version of this International Standard to which the volume is expected to conform.
The character in this field shall be a digit.
The digit 4 shall indicate the present version of this International Standard.
8.1.3.2 Other Volume Header Labels (VOL2 to VOL9)
Other Volume Header Labels shall be optional. If present, they shall contain implementation-defined
information and shall have the layout shown in Table 3.
© ISO/IEC 2012 – All rights reserved 13

Table 3 — Other Volume Header Labels (VOL2 to VOL9)
BP Field name L Content
1 to 3 Label Identifier 3 VOL
4 Label Number 1 Digits 2 to 9
5 to 80 (Reserved for implementation use) 76 Not specified

8.1.3.2.1 Label Identifier (BP 1 to 3)
This field shall specify the Label Identifier.
The characters in this field shall be VOL.
8.1.3.2.2 Label Number (BP 4)
This field shall specify the Label Number.
The character in this field shall be one of the digits TWO to NINE.
8.1.3.2.3 Field reserved for implementation use (BP 5 to 80)
This field shall be reserved for implementation use.
This International Standard neither specifies nor restricts the bit combinations which may be recorded in this
field, nor does it specify any meaning for these bit combinations.
8.1.4 Installation Volume Label Set (UVL1 to UVL9)
An Installation Volume Label Set is optional. If present, it shall comprise at least one Installation Volume Label
and at most nine such labels. They shall have the layout shown in Table 4.
Table 4 — Installation Volume Label Set (UVL1 to UVL9)
BP Field name L Content
1 to 3 Label Identifier 3 UVL
4 Label Number 1 Digits 1 to 9
5 to 80 (Reserved for installation use) 76 Not specified

8.1.4.1 Label Identifier (BP 1 to 3)
This field shall specify the Label Identifier.
The characters in this field shall be UVL.
8.1.4.2 Label Number (BP 4)
This field shall specify the Label Number.
The Character in this field shall be one of the digits ONE to NINE.
14 © ISO/IEC 2012 – All rights reserved

8.1.4.3 Field reserved for installation use (BP 5 to 80)
This field shall be reserved for installation use.
This International Standard neither specifies nor restricts the bit combinations which may be recorded in this
field, nor does it specify any meaning for these bit combinations.
8.1.5 File Header Label Set (HDR1 to HDR9)
A File Header Label Set shall be a label set comprising at least two File Header Labels and at most nine such
labels.
8.1.5.1 First File Header Label (HDR1)
The First File Header Label shall identify the file section, specify the position of the file section within a file set,
and specify certain attributes of the file section. (see Table 5)
Table 5 — First File Header Label (HDR1)
BP Field name L Content
1 to 3 Label Identifier 3 HDR
4 Label Number 1 1
5 to 21 File Identifier 17 a
...