<< Order of Path Table Records | Recording of descriptor fields >>

Record structure

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6.9.2

Path Table Group
A Path Table shall be either a Type L Path Table or a Type M Path Table. In a Type L Path Table, a numerical
value shall be recorded according to 7.2.1 if represented as a 16-bit number and according to 7.3.1 if represented
as a 32-bit number.

In a Type M Path Table, a numerical value shall be recorded according to 7.2.2 if represented as a 16-bit number
and according to 7.3.2 if represented as a 32-bit number.

A Path Table Group shall comprise one or two identical Type L Path Tables and one or two identical Type M
Path Tables.

6.9.3

Recorded Occurrences of the Path Table
One or more Path Table Groups shall be recorded on a volume. The Primary Volume Descriptor shall identify
the size and locations of the constituent Path Tables of a Path Table Group. These Path Tables shall identify the
directories in the Directory Hierarchy which is identified by the Primary Volume Descriptor.

Corresponding to each additional Directory Hierarchy recorded on a volume an additional Path Table Group
shall be recorded on the volume. For each such Path Table Group, the corresponding Supplementary Volume
Descriptor shall identify the size and locations of its constituent Path Tables. These Path Tables shall identify the
directories in the corresponding Directory Hierarchy.

6.9.4

Consistency of Path Tables between volumes of a Volume Group

6.9.4.1

The contents of a Type L Path Table identified in a Primary Volume Descriptor shall be identical with the
contents of any other Type L Path Table identified in a Primary Volume Descriptor on a volume of the same
Volume Group.
The contents of a Type M Path Table identified in a Primary Volume Descriptor shall be identical with the
contents of any other Type M Path Table identified in a Primary Volume Descriptor on a volume of the same
Volume Group.

6.9.4.2

The contents of a Type L Path Table identified in a Supplementary Volume Descriptor shall be identical with
the contents of any other Type L Path Table identified in a Supplementary Volume Descriptor, having the
same volume set identification and identifying the same coded graphic character sets for use within selected
descriptor fields (see 7.4), on a volume of the same Volume Group.
The contents of a Type M Path Table identified in a Supplementary Volume Descriptor shall be identical with
the contents of any other Type M Path Table identified in a Supplementary Volume Descriptor, having the
same volume set identification and identifying the same coded graphic character sets for use within selected
descriptor fields (see 7.4), on a volume of the same Volume Group.

6.10 Record

structure

The information in a file may be organized as a set of records according to this clause.

6.10.1 Characteristics

A record shall be a sequence of bytes treated as a unit of information.

The length of a record shall be the number of bytes in the record.

A record shall be either a fixed-length record or a variable-length record.

All records in a file shall be either fixed-length records or variable-length records.

6.10.2

Measured Data Units (MDU)

6.10.2.1

Contents of an MDU
A Measured Data Unit shall contain either a fixed-length record or a variable-length record. An MDU shall
comprise an even number of bytes.

6.10.2.2

Relationship to File
Each MDU shall comprise a set of successive bytes of the file. The first or only MDU shall begin at the first
byte of the file. Each successive MDU shall begin at the byte in the file immediately following the last byte of
the preceding MDU.