ISO/IEC 13346-3:1999

INTERNATIONAL ISO/IEC
STANDARD 13346-3
Second edition
1999-06-01
Information technology — Volume and file
structure of write-once and rewritable
media using non-sequential recording for
information interchange —
Part 3:
Volume structure
Technologies de l'information — Structure de volume et de fichier de
moyens d'écriture unique et de réécriture utilisant un enregistrement non
séquentiel pour l'échange d'information —
Partie 3: Structure de volume
Reference number
B C
Contents
1 Scope .1
2 Parts references.1
3 Part interface.2
3.1 Input .2
3.2 Output .2
4 Conformance.2
4.1 Conformance of a medium .2
4.2 Conformance of an information processing system .3
5 Definitions .3
5.1 Anchor point.3
5.2 Cyclic Redundancy Check (CRC).3
5.3 Extent.3
5.4 Logical block.3
5.5 Logical sector.3
5.6 Logical volume.3
5.7 Partition .3
6 Notation .3
7 Basic types.3
7.1 Extent Descriptor.3
7.1.1 Extent Length (RBP 0).4
©  ISO/IEC 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
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Printed in Switzerland
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© ISO/IEC ISO/IEC 13346-3:1999(E)
7.1.2 Extent Location (RBP 4). 4
7.2 Descriptor tag . 4
7.2.1 Tag Identifier (RBP 0) . 4
7.2.2 Descriptor Version (RBP 2). 5
7.2.3 Tag Checksum (RBP 4) . 5
7.2.4 Reserved (RBP 5). 5
7.2.5 Tag Serial Number (RBP 6). 5
7.2.6 Descriptor CRC (RBP 8). 5
7.2.7 Descriptor CRC Length (RBP 10). 6
7.2.8 Tag Location (RBP 12) . 6
8 Volume structure . 6
8.1 Arrangement of information on a volume. 6
8.1.1 Sector numbers . 6
8.1.2 Logical sector . 6
8.2 Volume space. 6
8.3 Volume descriptors . 7
8.4 Volume Descriptor Sequence. 7
8.4.1 Contents of a Volume Descriptor Sequence. 7
8.4.2 Recording of the Volume Descriptor Sequence . 7
8.4.3 Prevailing descriptors . 8
8.4.4 Recording of descriptors. 9
8.5 Allocation of the volume space. 9
8.6 Volume set. 9
8.7 Partition . 10
8.8 Logical volume. 10
8.8.1 Logical blocks. 10
8.8.2 Logical volume integrity . 10
9 Volume recognition structures. 11
9.1 NSR Descriptor . 11
9.1.1 Structure Type (BP 0). 11
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9.1.2 Standard Identifier (BP 1).11
9.1.3 Structure Version (BP 6) .11
9.1.4 Reserved (BP 7) .11
9.1.5 Structure Data (BP 8).11
10 Volume data structures.12
10.1 Primary Volume Descriptor.12
10.1.1 Descriptor Tag (BP 0) .12
10.1.2 Volume Descriptor Sequence Number (BP 16).12
10.1.3 Primary Volume Descriptor Number (BP 20) .12
10.1.4 Volume Identifier (BP 24) .13
10.1.5 Volume Sequence Number (BP 56).13
10.1.6 Maximum Volume Sequence Number (BP 58) .13
10.1.7 Interchange Level (BP 60).13
10.1.8 Maximum Interchange Level (BP 62) .13
10.1.9 Character Set List (BP 64).13
10.1.10 Maximum Character Set List (BP 68) .13
10.1.11 Volume Set Identifier (BP 72).13
10.1.12 Descriptor Character Set (BP 200) .13
10.1.13 Explanatory Character Set (BP 264).13
10.1.14 Volume Abstract (BP 328).14
10.1.15 Volume Copyright Notice (BP 336) .14
10.1.16 Application Identifier (BP 344).14
10.1.17 Recording Date and Time (BP 376) .14
10.1.18 Implementation Identifier (BP 388).14
10.1.19 Implementation Use (BP 420) .14
10.1.20 Predecessor Volume Descriptor Sequence Location (BP 484).14
10.1.21 Flags (BP 488) .14
10.1.22 Reserved (BP 490) .15
10.2 Anchor Volume Descriptor Pointer.15
10.2.1 Descriptor Tag (BP 0) .15
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10.2.2 Main Volume Descriptor Sequence Extent (BP 16) . 15
10.2.3 Reserve Volume Descriptor Sequence Extent (BP 24) . 15
10.2.4 Reserved (BP 32) . 15
10.3 Volume Descriptor Pointer . 15
10.3.1 Descriptor Tag (BP 0). 16
10.3.2 Volume Descriptor Sequence Number (BP 16). 16
10.3.3 Next Volume Descriptor Sequence Extent (BP 20) . 16
10.3.4 Reserved (BP 28) . 16
10.4 Implementation Use Volume Descriptor . 16
10.4.1 Descriptor Tag (BP 0). 16
10.4.2 Volume Descriptor Sequence Number (BP 16). 16
10.4.3 Implementation Identifier (BP 20) . 17
10.4.4 Implementation Use (BP 52) . 17
10.5 Partition Descriptor . 17
10.5.1 Descriptor Tag (BP 0). 17
10.5.2 Volume Descriptor Sequence Number (BP 16). 17
10.5.3 Partition Flags (BP 20) . 17
10.5.4 Partition Number (BP 22) . 18
10.5.5 Partition Contents (BP 24) . 18
10.5.6 Partition Contents Use (BP 56). 18
10.5.7 Access Type (BP 184) . 18
10.5.8 Partition Starting Location (BP 188) . 18
10.5.9 Partition Length (BP 192). 19
10.5.10 Implementation Identifier (BP 196) . 19
10.5.11 Implementation Use (BP 228) . 19
10.5.12 Reserved (BP 356) . 19
10.6 Logical Volume Descriptor . 19
10.6.1 Descriptor Tag (BP 0). 19
10.6.2 Volume Descriptor Sequence Number (BP 16). 19
10.6.3 Descriptor Character Set (BP 20). 19
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10.6.4 Logical Volume Identifier (BP 84).20
10.6.5 Logical Block Size (BP 212).20
10.6.6 Domain Identifier (BP 216) .20
10.6.7 Logical Volume Contents Use (BP 248).20
10.6.8 Map Table Length (=MT_L) (BP 264).20
10.6.9 Number of Partition Maps (=N_PM) (BP 268) .20
10.6.10 Implementation Identifier (BP 272).20
10.6.11 Implementation Use (BP 304) .20
10.6.12 Integrity Sequence Extent (BP 432) .20
10.6.13 Partition Maps (BP 440).20
10.7 Partition maps.21
10.7.1 Generic partition map.21
10.7.2 Type 1 Partition Map.21
10.7.3 Type 2 Partition Map.22
10.8 Unallocated Space Descriptor.22
10.8.1 Descriptor Tag (BP 0) .23
10.8.2 Volume Descriptor Sequence Number (BP 16).23
10.8.3 Number of Allocation Descriptors (=N_AD) (BP 20).23
10.8.4 Allocation Descriptors (BP 24) .23
10.9 Terminating Descriptor .23
10.9.1 Descriptor Tag (BP 0) .23
10.9.2 Reserved (BP 16) .23
10.10 Logical Volume Integrity Descriptor .23
10.10.1 Descriptor Tag (BP 0) .24
10.10.2 Recording Date and Time (BP 16) .24
10.10.3 Integrity Type (BP 28).24
10.10.4 Next Integrity Extent (BP 32) .24
10.10.5 Logical Volume Contents Use (BP 40).24
10.10.6 Number of Partitions (=N_P) (BP 72) .24
10.10.7 Length of Implementation Use (=L_IU) (BP 76) .25
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10.10.8 Free Space Table (BP 80). 25
10.10.9 Size Table (BP N_P·4+80). 25
10.10.10 Implementation Use (BP N_P·8+80) . 25
11 Levels of medium interchange. 25
11.1 Level 1. 25
11.2 Level 2. 26
11.3 Level 3. 26
12 Requirements for the description of systems . 26
13 Requirements for an originating system. 26
13.1 General . 26
13.2 Mandatory access by user. 26
13.2.1 Descriptors. 26
13.3 Optional access by user . 27
13.3.1 Descriptors. 27
13.3.2 Multivolume volume sets. 27
14 Requirements for a receiving system. 28
14.1 General . 28
14.2 Mandatory access by user. 28
14.2.1 Descriptors. 28
Annex A (informative) Changes from ISO/IEC 13346-3:1995 to this second edition. 29
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Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission)
form the specialised system for worldwide standardisation. National Bodies that are members of ISO or IEC
participate in the development of International Standards through technical committees established by the
respective organisation to deal with particular fields of technical activity. ISO and IEC technical committees
collaborate in fields of mutual interest. Other international organisations, governmental and non-governmental, in
liaison with ISO and IEC, also take part in this work.
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 of an International Standard requires approval by at least 75% of the national bodies casting a vote.
International Standard ISO/IEC 13346-3 was prepared by ECMA, (as Standard ECMA-167) 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.
This second edition cancels and replaces the first edition (ISO/IEC 13346-3:1995), which has been technically
revised.
ISO/IEC 13346 consists of the following parts, under the general title Information technology — Volume and file
structure of write-once and rewritable media using non-sequential recording for information interchange:
 Part 1: General
 Part 2: Volume and boot block recognition
 Part 3: Volume structure

Part 4: File structure
 Part 5: Record structure
Annex A of this part of ISO/IEC 13346 is for information only.
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Introduction
ISO/IEC 13346 is a volume and file structure standard for interchanging files and as such, it is a peer to existing
volume and file structure standards such as ISO 9293 and ISO 9660. It is rather different from those standards in at
least two important ways. Firstly, it offers much more functionality, mainly because of user needs for increased
character set support and for more powerful file system features. Secondly, it acknowledges the separate concerns
of booting, volume structure and file system structure. Rather than bundling these different functions together,
ISO/IEC 13346 carefully segregates these functions into separate parts and describes in detail how those parts fit
together. It is expected that future volume and file structure standards will fit into this framework, rather than building
other distinct and incompatible formats.
ISO/IEC 13346 is published in five Parts. Part 1 - general - specifies references, definitions, notations and basic
structures used in the other four Parts. Part 2 - volume and boot block recognition - specifies formats and system
requirements for recognising the volume structures on a medium and booting from a medium. Part 3 - volume
structure - specifies how to record various volume-related entities such as volumes, volume sets and logical
volumes. Part 4 - file structure - specifies how to record and interpret files, both file data and file attributes, and file
hierarchies within logical volumes. Part 5 - record structure - specifies how to record and interpret file data encoded
as records.
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INTERNATIONAL STANDARD  ISO/IEC ISO/IEC 13346-3:1999(E)
Information technology — Volume and file structure of write-once
and rewritable media using non-sequential recording for
information interchange —
Part 3:
Volume structure
1 Scope
ISO/IEC 13346 specifies a format and associated system requirements for volume and boot block recognition,
volume structure, file structure and record structure for the interchange of information on media between users of
information processing systems.
The media shall be recorded as if the recording of sectors may be done in any order.
Note 1 - The medium is not restricted to being of only one type; the type of medium may be either write once, or read only, or
rewritable, or a combination of these types.
ISO/IEC 13346 consists of the following five Parts:
Part 1: General
Part 2: Volume and Boot Block Recognition
Part 3: Volume Structure
Part 4: File Structure
Part 5: Record Structure
Annex A - ICB Strategies, is part of ISO/IEC 13346-4.
This part of ISO/IEC 13346 specifies a format and associated system requirements for volume structure by
specifying:
 the attributes of a volume and the descriptors recorded on it;
 the relationship among volumes of a volume set;
 the attributes of a partition of a volume;
 the attributes of a logical volume and the descriptors recorded on it;
 levels of medium interchange;
 requirements for the processes which are provided within information processing systems, to enable
information to be interchanged between different systems; for this purpose, it specifies the functions to be
provided within systems which are intended to originate or receive media which conform to this part of
ISO/IEC 13346.
2 Parts references
The first digit of a reference within ISO/IEC 13346 identifies the Part, e.g. 2/5 refers to clause 5 in ISO/IEC 13346-2,
and figure 4/3 refers to figure 3 in ISO/IEC 13346-4.
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3 Part interface
This clause specifies the interface of this part of ISO/IEC 13346 to other standards or Parts.
3.1 Input
This part of ISO/IEC 13346 requires the specification of the following by another standard or Part.
 A standard for recording (see 1/5.10).
 The size of a logical sector (see 3/8.1.2) of a volume.
 If the volume is recorded according to ISO/IEC 13346-2, a volume recognition sequence specified by
ISO/IEC 13346-2 shall contain the descriptor described in 3/9.1 recorded at least once.
 If the volume is recorded according to ISO/IEC 13346-2, the volume recognition space (see 2/8.2) shall be the
entire volume.
 If the volume is recorded according to ISO/IEC 13346-2, the initial sector in the volume (see2/3.1) shall be the
first sector of the volume.
 Information to be recorded in the Partition Contents Use field of a Partition Descriptor (see 3/10.5.6).
 Information to be recorded in the Logical Volume Contents Use field of a Logical Volume Descriptor (see
3/10.6.7).
3.2 Output
This part of ISO/IEC 13346 specifies the following which may be used by other standards or Parts.
 Volume sets of one or more volumes (see 3/8.6).
 A volume space for a volume (see 3/8.2).
 Logical sectors of a fixed size for a volume (see 3/8.1.2).
 Partitions (see 3/8.7).
 Logical volumes composed of partitions (see 3/8.8).
 Numeric identification of the partitions within a logical volume (see 3/8.8).
 Logical blocks of a fixed size for a logical volume.
 The logical block size for a logical volume.
 Attributes of a volume.
 Attributes of a logical volume.
 Attributes of a partition.
 An indication that a volume may have been recorded to this part of ISO/IEC 13346 (see 3/9.1).
4 Conformance
4.1 Conformance of a medium
A medium shall be in conformance with ISO/IEC 13346 when it conforms to a standard for recording (see 1/5.10)
and information recorded on sectors of the medium conform to the specifications of ISO/IEC 13346-1 and one or
more of ISO/IEC 13346-2, -3, -4 and -5. A statement of conformance shall identify the sectors of the medium on
which information is recorded according to the specifications of ISO/IEC 13346, and the Parts and the levels of
medium interchange (see 1/10, 3/11, and 4/15) to which the contents of those sectors of the medium conform.
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ISO/IEC ISO/IEC 13346-3:1999(E)
4.2 Conformance of an information processing system
An information processing system shall be in conformance with ISO/IEC 13346 if it meets the requirements
specified in ISO/IEC 13346-1 and one or more of ISO/IEC 13346-2, -3, -4 and -5 either for an originating system
(see 2/13, 3/13, 4/17 and 5/11) or for a receiving system (see 2/13, 3/14, 4/18 and 5/12) or for both types of system.
A statement of conformance shall identify the Parts, and the levels of the requirements for each of those Parts,
which can be met by the system.
5 Definitions
In addition to the definitions of ISO/IEC 13346-1 (see 1/5), the following definitions apply for this part of
ISO/IEC 13346.
5.1 Anchor point
One of a specified set of logical sector numbers at which descriptors, that identify an extent of a Volume Descriptor
Sequence, may be recorded.
5.2 Cyclic Redundancy Check (CRC)
A method for computing a signature of a sequence of bytes.
5.3 Extent
A set of logical sectors whose logical sector numbers (see 3/8.1.2.1) form a continuous ascending sequence. The
address, or location, of an extent is the first logical sector number in that sequence.
5.4 Logical block
The unit of allocation of a logical volume.
5.5 Logical sector
The unit of allocation of a volume.
5.6 Logical volume
A nonempty set of partitions.
5.7 Partition
An extent of logical sectors within a volume.
6 Notation
The notation of ISO/IEC 13346-1 (see 1/6) applies to this part of ISO/IEC 13346.
7 Basic types
In addition to the basic types of ISO/IEC 13346-1 (see 1/7), the following basic types apply for this part of
ISO/IEC 13346.
7.1 Extent Descriptor
An Extent Descriptor, hereafter designated as extent_ad, shall be recorded in the format shown in figure 3/1.
RBP Length Name Contents
0 4 Extent Length Uint32 (1/7.1.5)
4 4 Extent Location Uint32 (1/7.1.5)
Figure 1 — extent_ad format
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7.1.1 Extent Length (RBP 0)
This field shall indicate the length of the extent, in bytes, identified by the Extent Location field. The length shall be
less than 2 . Unless otherwise specified, the length shall be an integral multiple of the logical sector size.
7.1.2 Extent Location (RBP 4)
This field shall specify the location of the extent, as a logical sector number. If the extent's length is 0, no extent is
specified and this field shall contain 0.
7.2 Descriptor tag
Certain descriptors specified in this part of ISO/IEC 13346 have a 16 byte structure, or tag, recorded at the start of
the descriptor. The tag shall be recorded with the format shown in figure 3/2.
Note 2 - There are two main motivations for using a generic tag structure. The first is that most descriptors need to handle
common issues of CRCs and format versions. The second motivation is to support recovery after the medium has been
damaged or corrupted in some (unspecified) way. With the tag described here, structures are self identifying and can be
verified with very little context.
RBP Length Name Contents
0 2 Tag Identifier Uint16 (1/7.1.3)
2 2 Descriptor Version Uint16 (1/7.1.3)
4 1 Tag Checksum Uint8 (1/7.1.1)
5 1 Reserved #00 byte
6 2 Tag Serial Number Uint16 (1/7.1.3)
8 2 Descriptor CRC Uint16 (1/7.1.3)
10 2 Descriptor CRC Length Uint16 (1/7.1.3)
12 4 Tag Location Uint32 (1/7.1.5)
Figure 2 — tag format
7.2.1 Tag Identifier (RBP 0)
This field shall specify an identification of the descriptor type. Type 0 shall specify that the format of this descriptor is
not specified by this part of ISO/IEC 13346. Types 1-7 and 9 are specified as shown in figure 3/3. Type 8 is
specified identically in this part of ISO/IEC 13346 and ISO/IEC 13346-4. Types 256-265 are specified in
ISO/IEC 13346-4. All other types are reserved for future standardisation. The descriptor types specified by this part
of ISO/IEC 13346 are shown in figure 3/3.
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ISO/IEC ISO/IEC 13346-3:1999(E)
Type Interpretation
1 Primary Volume Descriptor (3/10.1)
2 Anchor Volume Descriptor Pointer (3/10.2)
3 Volume Descriptor Pointer (3/10.3)
4 Implementation Use Volume Descriptor (3/10.4)
5 Partition Descriptor (3/10.5)
6 Logical Volume Descriptor (3/10.6)
7 Unallocated Space Descriptor (3/10.8)
8 Terminating Descriptor (3/10.9 and 4/14.2)
9 Logical Volume Integrity Descriptor (3/10.10)
Figure 3 — Descriptor interpretation
7.2.2 Descriptor Version (RBP 2)
This field shall specify the version of this descriptor. This value shall be 2 or 3. The value 3 shall indicate the
structure of this part of ISO/IEC 13346. The value 2 shall indicate the structure of this part of ISO/IEC 13346. See
3/13.1 and 3/14.1 for requirements.
Note 3 - Structures with version 2 descriptors may be on the medium due to changing the medium from NSR02 to NSR03
without rewriting all descriptors as version 3. Originating systems shall record a 3 in this field; receiving systems shall allow a 2
or 3 (see 3/13.1 and 3/14.1).
7.2.3 Tag Checksum (RBP 4)
This field shall specify the sum modulo 256 of bytes 0-3 and 5-15 of the tag.
7.2.4 Reserved (RBP 5)
This field shall be reserved for future standardisation and shall be set to 0.
7.2.5 Tag Serial Number (RBP 6)
This field shall specify an identification of a set of descriptors. If the field contains 0, then no such identification is
specified.
Note 4 - This field can be used to distinguish between groups of descriptors. For example, when reusing rewritable media, an
implementation might choose a different serial number from the previous use when initialising a volume. Thus, a disaster
recovery mechanism can avoid recovering prior and unintended data. The only alternative to this scheme would be to force
volume initialisation to clear the volume.
7.2.6 Descriptor CRC (RBP 8)
This field shall specify the CRC of the bytes of the descriptor starting at the first byte after the descriptor tag. The
number of bytes shall be specified by the Descriptor CRC Length field. The CRC shall be 16 bits long and be
generated by the CRC-ITU-T polynomial (see ITU-T V.41):
16 12 5
x + x + x + 1
Note 5 - As an example, the CRC of the three bytes #70 #6A #77 is #3299. Implementations can avoid calculating the CRC by
setting the Descriptor CRC Length to 0, as then the Descriptor CRC shall be 0.
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7.2.7 Descriptor CRC Length (RBP 10)
This field specifies how many bytes were used in calculating the Descriptor CRC.
7.2.8 Tag Location (RBP 12)
This field shall specify the number of the logical sector containing the first byte of the descriptor.
Note 6 - The location of the tag may appear to be redundant but its primary purpose is to make it extremely likely that if the first
16 bytes of a logical sector or logical block is a consistent descriptor tag, then it is a descriptor tag.
8 Volume structure
8.1 Arrangement of information on a volume
8.1.1 Sector numbers
Each sector of a volume shall be identified by a unique sector number. Sector numbers shall be consecutive
integers assigned in an ascending sequence, in the order of ascending physical address of the volume as specified
in the relevant standard for recording (see 1/5.10). Sector number 0 shall be assigned to the sector having the
lowest physical address of the volume.
8.1.2 Logical sector
The sectors of a volume shall be organised into logical sectors of equal length. The length of a logical sector shall
be referred to as the logical sector size and shall be an integral multiple of 512 bytes. The logical sector size shall
be not less than the size of the smallest sector of the volume. Each logical sector shall begin in a different sector,
starting with the sector having the next higher sector number than that of the last sector constituting the previous, if
any, logical sector of the volume. The first byte of a logical sector shall be the first byte of the sector in which it
begins, and if the size of this sector is smaller than the logical sector size, then the logical sector shall comprise a
sequence of constituent sectors with consecutive ascending sector numbers.
8.1.2.1 Logical sector numbers
Each logical sector of a volume shall be identified by a unique logical sector number. Logical sector numbers shall
be consecutive integers assigned in ascending sequence, in the order of ascending sector numbers of the volume.
Logical sector number 0 shall be assigned to the logical sector beginning in sector number 0. The largest logical
sector number of a volume shall be greater than 256.
8.1.2.2 Recording of logical sectors
Any unrecorded constituent sector of a logical sector shall be interpreted as containing all #00 bytes. Within the
sector containing the last byte of a logical sector, the interpretation of any bytes after that last byte is not specified
by this part of ISO/IEC 13346.
A logical sector is unrecorded if the standard for recording allows detection that a sector has been unrecorded and
all of the logical sector's constituent sectors are unrecorded. A logical sector should either be completely recorded
or unrecorded.
8.2 Volume space
The information on a volume shall be recorded in the set of all logical sectors in a volume. This set shall be referred
to as the volume space of the volume. The bytes in the volume space shall be numbered with consecutive integers
assigned in ascending sequence starting with 0. Let s be the number of bytes in a logical sector; then byte b of the
volume space is byte rem(b,s) of logical sector ip(b/s).
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ISO/IEC ISO/IEC 13346-3:1999(E)
8.3 Volume descriptors
Characteristics of the volume shall be specified by volume descriptors recorded in Volume Descriptor Sequences as
described in 3/8.4.2.
A volume descriptor shall be one of the following types:
 Primary Volume Descriptor (see 3/10.1)

...