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System Area and Data Area

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starting with 0 for the Logical Sector containing the sector having the lowest Physical Address which may
contain recorded information. The numbering shall continue through successive Logical Sectors, each of which
begins with the sector with the next higher Physical Address than that of the last sector constituting the previous
Logical Sector.

6.1.3 Volume

Space

The information on a volume shall be recorded in the set of all Logical Sectors on the volume. This set shall be
referred to as the Volume Space of the volume.

The bytes in the Volume Space shall be numbered consecutively. The numbering shall start with 1, which shall
be assigned to the first byte of the first Logical Sector of the Volume Space. The numbering shall continue
through successive bytes of the first Logical Sector, and then through successive bytes of each successive
Logical Sector, of the Volume Space.

6.2

Arrangement of the Volume Space

6.2.1

System Area and Data Area
The Volume Space shall be divided into a System Area and a Data Area.

The System Area shall occupy the Logical Sectors with Logical Sector Numbers 0 to 15. The System Area shall
be reserved for system use. Its content is not specified by this Standard.

The Data Area shall occupy the remaining Logical Sectors of the Volume Space.

6.2.2 Logical

Block

The Volume Space shall be organized into Logical Blocks. Each Logical Block shall consist of 2

n+9

bytes,

where n equals 0 or a positive integer. The number of bytes in a Logical Block shall be referred to as the Logical
Block size which shall not be greater than the Logical Sector size.

Each Logical Block shall be identified by a unique Logical Block Number. Logical Block Numbers shall be
integers assigned in ascending order starting with 0. Logical Block Number 0 shall be assigned to the Logical
Block which begins with the first byte of the Volume Space. Each successive Logical Block Number shall be
assigned to the Logical Block which begins with the byte in the Volume Space immediately following the last
byte of the preceding Logical Block.

6.3

Arrangement of the Data Area

File Sections shall be recorded in the Data Area. More than one File Section of a file may be recorded on the same
volume.

The following types of descriptors shall be recorded in the Data Area to describe the use of the Data Area:

- Volume Descriptors
- File Descriptors
- Directory Descriptors
- Path Tables

The Volume Descriptors shall be recorded in consecutively numbered Logical Sectors starting with the Logical
Sector having Logical Sector Number 16. The Logical Sectors in the Data Area shall be available for the
assignment of Volume Partitions and the recording of File Sections, File Descriptors, Directory Descriptors and
Path Tables.

Each File Section shall be recorded in an Extent, and shall be identified by a descriptor in a directory. An Extended
Attribute Record can be associated with the File Section. If present, it shall be recorded in the same Extent as the
associated File Section, and shall be identified by the descriptor that identifies the associated File Section. Each
directory shall be recorded as a file in a single Extent, and shall be identified by a Directory Descriptor either in
another directory or in a Volume Descriptor. Each directory shall also be identified by a record in a Path Table.
Each Path Table shall be identified in a Volume Descriptor.

Space within the Data Area may be assigned to one or more Volume Partitions. Each Volume Partition shall be
recorded in an Extent and shall be identified by a Volume Descriptor.