WO2005122705A2

WO2005122705A2 - Recording medium, and method and apparatus for reformatting the same

Info

Publication number: WO2005122705A2
Application number: PCT/KR2005/001884
Authority: WO
Inventors: Yong Cheol Park
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2004-06-21
Filing date: 2005-06-17
Publication date: 2005-12-29
Anticipated expiration: 2006-12-21
Also published as: US7729208B2; AU2005253886A1; MY144178A; TW200603123A; JP4477671B2; EP1759384B1; BRPI0512271A; KR101137355B1; CN100545917C; TWI386931B; CN1965353A; EP2075791A1; ATE422091T1; EP1759384A2; US20050281167A1; KR20060046157A; RU2416829C2; WO2005122705A3; EP2075791B1; DE602005025168D1

Abstract

A recording medium, and a method and apparatus for reformatting the recording medium are disclosed. The method for reformatting a recording medium includes the steps of: (a) reading a plurality of physical access control information of the recording medium in a plurality of recording units; and (b) performing an initialization process for each recording unit upon receiving a reformatting command associated with the plurality of recording units, wherein the initialization process is differently performed according to an attribute of information recorded in each recording unit. Therefore, the PAC area contained in a high-density optical disc can be efficiently reformatted.

Description

[DESCRIPTION] RECORDING MEDIUM, AND METHOD AND APPARATUS FOR REFORMATTING THE SAME

Technical Field

The present invention relates to a recording medium, and a method and apparatus for

reformatting the recording medium, and more particularly, to a method for reformatting a

specific management area contained in the recording medium.

Background Art

Generally, there has been widely used an optical disc acting as a recording medium

capable of recording a large amount of data therein. Particularly, there has been newly

developed a high-density optical recording . medium capable of recording/storing high-

quality video data and high-quality audio data for a long period of time, for example, a

Blu-ray Disc (BD).

The BD acting as the next-generation recording medium has been considered to be the next-

generation optical recording solution capable of recording/storing much more data than a

conventional DVD. In recent times, the international standard technical specification

associated with the BD has been established along with those of other digital devices.

Although many developers have conducted intensive research into the introduction of a

PAC (Physical Access Control) area in the technical standard of the BD, the technical standard for the BD has not yet been established, so that the developers have difficulty in

developing the completed optical recording/reproducing apparatus.

Disclosure of Invention

Accordingly, the present invention is directed to a recording medium, and a method and

apparatus for reformatting the recording medium that substantially obviate one or more

problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method and apparatus for recording PAC

information in a recording medium, and reformatting the recording medium on a recording

unit basis.

Additional advantages, objects, and features of the invention will be set forth in part in the

description which follows and in part will become apparent to those having ordinary skill in

the art upon examination of the following or may be learned from practice of the invention.

The objectives and other advantages of the invention may be realized and attained by the

structure particularly pointed out in the written description and claims hereof as well as the

appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the

invention, as embodied and broadly described herein, a method for reformatting a recording

medium includes the steps of (a) reading a plurality of physical access control information

of the recording medium in a plurality of recording units, and (b) performing an initialization process for each recording unit upon receiving a reformatting command

associated with the plurality of recording units, wherein the initialization process is

differently performed according to an attribute of information recorded in each recording

unit.

In another aspect of the present invention, a method for reformatting a recording medium

includes the steps of (a) recognizing type information of a PAC (Physical Access Control)

cluster using PAC_ID information contained in each PAC cluster of a PAC area, (b) if the

PACJD information is indicative of a non-primary PAC cluster, changing PAC status

information and the PACJD information to other information during a reformatting

operation, and (c) if the PAC_ID information is indicative of a primary PAC cluster,

maintaining the PAC status information and the PACJD information during the

reformatting operation.

cluster using PACJD information contained in each PAC cluster of a PAC area, (b) if the

operation, and initializing all information contained in the PAC cluster, and (c) if the

PACJD information is indicative of a primary PAC cluster, maintaining the PAC status

information and the PACJOD information during the reformatting operation. In another aspect of the present invention, an apparatus for reformatting a recording

medium includes a controller for generating a request for reformatting the recording

medium, and a recording/reproducing unit for reformatting the recording medium upon

receiving the reformatting request from the controller, recognizing type information of a

PAC cluster using PACJOD information contained in each PAC (Physical Access Control)

cluster, changing PAC status information and the PACJD information to other information

during a reformatting operation when the PACJD information is indicative of a non-

primary PAC cluster, and maintaining the PAC status information and the PACJD

information without any change during the reformatting operation when the PACJQD

information is indicative of a primary PAC cluster.

In a further aspect of the present invention, an apparatus for reformatting a recording

PAC cluster using PACJD information contained in each PAC (Physical Access Control)

cluster, initializing PAC status information, the PACJD information, and all information

contained in the PAC cluster during a reformatting operation when the PACJD information

is indicative of a non-primary PAC cluster, and maintaining the PAC status information and

the PACJD information without any change during the reformatting operation when the

PACJD information is indicative of a primary PAC cluster. It is to be understood that both the foregoing general description and the following detailed

description of the present invention are exemplary and explanatory and are intended to

provide further explanation of the invention as claimed.

Brief Description of Drawings

The accompanying drawings, which are included to provide a further understanding of the

invention and are incorporated in and constitute a part of this application, illustrate

embodiment(s) of the invention and together with the description serve to explain the

principle of the invention. In the drawings:

FIG. 1 shows a physical structure of a recording medium according to the present invention;

FIG. 2 shows information contained in a PAC cluster of the recording medium according to

the present invention;

FIG. 3 is a block diagram illustrating an optical recording/reproducing apparatus according

to the present invention; and

FIGS. 4 and 5 are flow charts illustrating a method for reformatting the recording medium

according to the present invention.

Best Mode For Carrying Out the Invention

Reference will now be made in detail to the preferred embodiments of the present invention,

examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like

parts.

Prior to describing the present invention, it should be noted that most terms disclosed in the

present invention correspond to general terms well known in the art, but some terms have

been selected by the applicant as necessary and will hereinafter be disclosed in the

following description of the present invention. Therefore, it is preferable that the terms

defined by the applicant be understood on the basis of their meanings in the present

invention.

A recording medium for use in the present invention is indicative of all recordable mediums,

for example, an optical disc, a magnetic disc, and a magnetic tape, etc.

For the convenience of description and better understanding of the present invention, the

optical disc will hereinafter be exemplarily used as the above-mentioned recording medium

in the present invention.

The term "reformatting" is indicative of a process for re-initializing recording medium

format information due to a specific cause generated while the recording medium such as a

re-recordable optical disc is used. Particularly, although the reformatting operation must be

performed only when a reformatting allowable condition has been provided in order to

protect old data recorded in the recording medium from danger, the present invention firstly

assumes that the reformatting allowable condition has been provided, and will disclose a

method for reformatting a specific management area (e.g., a PAC area) of the recording medium under the above assumption.

The term "PAC" is indicative of a process for controlling a physical access of a recording

medium. For example, the PAC area contained in the recording medium is indicative of a

specific area in which PAC-associated control information is recorded, a PAC cluster is

indicative of a single recording unit contained in the PAC area, and a detailed description

thereof will hereinafter be given with reference to FIGS. 1 and 2.

FIG. 1 shows a physical structure of a recording medium according to the present invention.

For example, an optical disc serving as the recording medium includes a data area for

recording user-desired data and a lead-in area for recording a variety of information capable

of managing the disc. The lead-in area is contained in an inner area of the disc.

One end of the lead-in area includes a PAC area. The PAC area includes a plurality of

recording units, for example, n PAC clusters (PAC cluster 1 ~ PAC cluster n).

In other words, a single PAC cluster includes PAC information for each disc. Detailed

information contained in the PAC cluster will hereinafter be described in the following

description.

Although only one PAC area contained in the disc is exemplarily shown in FIG. 1, it should

be noted that this example is provided for the convenience of description. For example, if

the recording medium includes two PAC areas, the same information is recorded in the two

PAC areas, such that information recorded in the PAC areas can be more reliably protected

from danger. Generally, the lead-in area includes a DMA (Defect Management Area) for managing a disc

defect and a general management function. The DMA records a DDS (Disc Definition

Structure) therein.

Status information indicative of a status of each PAC cluster contained in the above-

mentioned PAC area is recorded in the DDS. For example, two bits are allocated to each

PAC cluster, such that they are able to indicate status information of each PAC cluster.

For example, if status information of a PAC cluster is a predetermined number "00", this

PAC cluster is indicative of an unused PAC cluster as denoted by "Unrecorded" in FIG. 1.

If status information of a PAC cluster is a predetermined number "01", this PAC cluster is

currently reusable even if it has been previously used, as denoted by "Available for re-use"

in FIG. 1. If status information of a PAC cluster is a predetermined number "10", this PAC

cluster is indicative of a specific PAC cluster in which invalid information is recorded, as

denoted by "Invalid" in FIG. 1. If status information of a PAC cluster is a predetermined

number "11", this PAC cluster is indicative of a specific PAC cluster in which current valid

information is recorded, as denoted by "Valid" in FIG. 1.

Therefore, the optical recording/reproducing apparatus shown in FIG. 3 detects PAC cluster

status information contained in the DDS, so that it can recognize current status information

of all PAC clusters contained in each PAC area.

the present invention. Referring to FIG. 2, one cluster acting as a recording unit includes 32 data frames. A single

data frame includes data of 2048 bytes.

In more detail, some parts of a first data frame (Data Frame 0) include general information

associated with a corresponding PAC cluster as PAC header information. The remaining 31

data frames (Data Frame 1 ~ Data Frame 31), and the remaining areas other than the

header information of the first data frame (Data Frame 0) include unique information of a

corresponding PAC cluster. Needless to say, the last data frame (Data Frame 31) may be

left as a reserved area as necessary, as shown in FIG. 2.

PAC header information recorded in some parts of the first data frame (Data Frame 0)

contained in the PAC cluster is used as recognition information indicative of a

corresponding PAC cluster type. The PAC header information includes a first field

"PACJD", a second field "PAC Format" for recording format version information of the

PAC cluster, and a third field "Update count" for recording the number of update times.

In the case of an optical recording/reproducing apparatus incapable of recognizing the first

field "PACJD", the PAC header information includes a first field "Unknown PAC Rule"

for recording physical access control information of the disc and a second field "Unknown

PAC Entire_Disc_flags", and also includes segment information for designating a specific

area of the disc controlled by the first field "Unknown PAC Rule". Particularly, the disc

can include a maximum of 32 segment information units as necessary. The PAC header

information includes a first field "Number of Segments" indicative of the number of segments contained in a current PAC cluster and a plurality of fields "Segment "

(i=0~31) including position information of each segment contained in the disc.

In the case of an optical recording/reproducing apparatus capable of recognizing the field

"PACJD", the PAC header information includes a predetermined field "Known PAC

Entire_Disc_flags" capable of providing control information.

Also, a plurality of fields "PAC specific information" include unique general information of

a corresponding PAC cluster and control information thereof. The above-mentioned unique

general information and control information of the PAC cluster can be referred by the

optical recording/reproducing apparatus recognizing the field "PACJD" when a disc

recording/reproducing operation is performed.

Each PAC cluster has a data structure shown in FIG. 2, all bytes contained in a

corresponding field from among the above-mentioned fields are determined to be "OOh"

when the corresponding field is not used. Therefore, the value of "OOh" is able to designate

a current unused field.

For example, if the number of segments managed by the above corresponding PAC cluster

is 2, the field "Number of segments" holds a value of 2. A field "SegmentJ)" records a

start address where a corresponding segment begins in the disc. A field "SegmentJ"

records an end address where the corresponding segment is ended. All bytes of the

remaining fields "Segment_2" ~ "Segment_31" are set to the value of "OOh", respectively.

In this way, all bytes contained in an unused field from among a plurality of fields "PAC specific information" can be set to the value "OOh", respectively.

Particularly, the field "PACJD" is critical to the present invention. In more detail, the

present invention is characterized in that different reformatting operations are performed

according to individual PAC cluster types. The above-mentioned PACJD information is

used as specific information capable of determining type information of a corresponding

PAC cluster.

The present invention largely classifies the PAC cluster into three PAC cluster types, i.e., an

unused PAC cluster indicative of an unused PAC cluster, a primary PAC cluster, and a non-

primary PAC cluster. In more detail, one or more primary PAC clusters must be

compulsorily included in the PAC area of each disc, and the non-primary PAC cluster is not

defined by the primary PAC cluster.

For example, if the PACJD field of 3 bytes in a specific PAC cluster is denoted by

"PACJD = 00 00 Oh", this PAC cluster is indicative of an unused PAC cluster, particularly,

an original unused PAC cluster. If the PACJD field of 3 bytes is denoted by "PACJD =

FF FF FFh", this PAC cluster is indicative of a previously used PAC cluster, particularly, a

now unused PAC cluster which was previously used, as denoted by "Previously Used and

Now Unused PAC Cluster" in FIG. 2.

For example, if the PACJD field of 3 bytes has a specific value predetermined as the

standard specification as denoted by "PACJD = 50 52 4Dh", this PAC cluster is indicative

of a primary PAC cluster. If the PACJD field of 3 bytes has another value different from the above-mentioned specific value, this PAC cluster is indicative of a non-primary PAC

cluster.

Therefore, although the non-primary PAC cluster can be set to a variety of PAC_ID values,

it must use the predetermined value determined as the standard specification. In other

words, when a specific non-primary PAC cluster is standardized, a corresponding PACJD

field is determined to be a specific value. Therefore, an optical recording/reproducing

apparatus manufactured before the non-primary PAC cluster is standardized cannot

recognize the PACJD value of the non-primary PAC cluster. In this way, if the optical

recording/reproducing apparatus cannot recognize the' PACJQD field of a specific PAC

cluster, a disc recording/reproducing access is controlled by a control scheme recorded in

the field "Unknown Rule" contained in the PAC cluster, as described above.

A method and apparatus for reformatting a recording medium will hereinafter be described

with reference to FIGS. 3-5.

to the present invention. Referring to FIG. 3, the optical recording/reproducing apparatus

largely includes a recording/reproducing unit 20 and a controller 12.

The recording/reproducing unit 20 includes an optical pickup unit 11 for reading data and

management information recorded in an optical disc; a servo unit 14 for controlling the

optical pickup unit 11; a signal processor 14 for restoring a reproduction signal received

from the optical pickup unit 11 to a desired signal value, or modulating a signal to be recorded into a signal recorded in the optical disc, such that it transmits the restored or

modulated result to the optical pickup unit 11; a memory 15 for temporarily storing the

management information read from the optical disc; and a microprocessor 16 for controlling

the above-mentioned operations. Particularly, a manufactured product composed of only

the recording/reproducing unit 20 is called a drive.

The controller 12 is adapted to control overall operations of the optical

recording/reproducing apparatus, receives a command from a user by interfacing with the

user, and transmits the received command to the microprocessor 16 contained in the

recording/reproducing unit 20, such that it allows the optical recording/reproducing

apparatus to perform operations associated with the user command. Particularly, the

controller 12 generates a recording/reproducing command using disc management

information received from the recording/reproducing unit 20, and then transmits the

recording/reproducing command to the recording/reproducing unit 20.

In association with the above-mentioned operations, an AV (Audio/Video) decoder 17

finally decodes output data upon receiving a control signal from the controller 12, and

transmits the decoded output data to the user-. An AV encoder 18 converts an input signal

into a specific format signal such as an MPEG2 transport stream) upon receiving a control

signal from the controller 12, and transmits the specific format signal to the signal processor

13 contained in the recording/reproducing unit 20, such that a desired signal can be

recorded in the optical disc. In the above-mentioned optical recording/reproducing apparatus, reformatting operations

according to the present invention will hereinafter be described with reference to FIGS. 4

and 5.

Upon receiving a command from a user, the controller 12 transmits a disc reformatting

command to the recording/reproducing unit 20. The reformatting command is allowable:

under a strict condition to protect data stored in a disc from danger. It should be noted that

the present invention assumes that the disc is capable of allowing the execution of the

reformatting command. The recording/reproducing unit 20 having received from the

reformatting command performs operations shown in FIGS. 4 and 5 while reformatting the

PAC area associated with the present invention.

FIG. 4 is a flow chart illustrating a method for reformatting the PAC area in accordance

with a preferred embodiment of the present invention.

Referring to FIG. 4, during the reformatting operation, the recording/reproducing unit 20

recognizes type information of a PAC cluster using the PACJD information of the PAC

cluster. If the PACJD information is indicative of a non-primary PAC cluster, the

recording/reproducing unit 20 changes the PAC status information and the PACJD

information to other information. Otherwise, if the PACJD information is indicative of a

primary PAC cluster, the recording/reproducing unit 20 maintains the PAC status

information and the PACJD information without any change.

In more detail, if the recording/reproducing unit 20 receives the reformatting command at step S10, it recognizes type information of each PAC cluster contained in the PAC area

using the PACJD information at step S20.

If type information of a PAC cluster is indicative of a primary PAC cluster as denoted by

"PACJD =50 52 4Dh" in FIG. 2 at step S20, the primary PAC cluster is indicative of a

PAC cluster which must remain after the reformatting operation has been performed.

Therefore, the recording/reproducing unit 20 must continuously maintain the PAC status

information and the PACJD information recorded in the DDS without any change at step

S30. But, it should be noted that the number of update times stored in the field "Update

Count" contained in the PAC cluster is increased by a predetermined number of 1 at step

S30.

If type information of a PAC cluster is determined to be an unused PAC cluster as denoted

by "PACJD -00 00 OOh" or "PACJD = FF FF FFh" in FIG. 2 at step S20, the PAC cluster

must remain after the reformatting operation has been performed. Therefore, the

recording/reproducing unit 20 must continuously maintain the PAC status information and

the PACJD information without any change at step S30.

If type information of a PAC cluster is indicative of a specific non-primary PAC cluster at

step S20, the PAC cluster must be changed to an unused PAC cluster during the

reformatting operation. Therefore, the PAC status information indicative of a status of a

corresponding PAC cluster contained in the DDS is changed from first data (e.g., "lib")

indicative of a valid status to second data (e.g., "01b") indicative of an available for re-use status at step S50. Also, the PACJD field contained in the PAC cluster must be changed to

specific information denoted by "PAC_ID = FF FF FFh" indicative of an unused PAC

cluster at step S51. In this case, there is no need to initialize all information stored in the

PAC cluster, and the reformatting operation is finished on the condition that the PAC status

information and the PACJD information are changed to other information at step S51.

The above-mentioned steps S20~S51 are repeated until reaching all PAC clusters .

contained in the PAC area at step S60. If the above-mentioned steps S20 — S51 are finished

for every PAC cluster type, the reformatting operation for the PAC area is also finished.

FIG. 5 is a flow chart illustrating a method for reformatting the PAC area in accordance

with another preferred embodiment of the present invention.

Referring to FIG. 5, during the reformatting operation, the recording/reproducing unit 20

recording/reproducing unit 20 initializes the PAC status information and the PACJOD

information. Otherwise, if the PACJD information is indicative of a primary PAC cluster,

the recording/reproducing unit 20 maintains the PAC status information and the PACJD

information without any change.

In other words, according to the second preferred embodiment shown in FIG. 5, during the

reformatting operation of the non-primary PAC cluster, all information contained in the

non-primary PAC cluster is initialized to the value of "OOh" or "FFh", differently from the first preferred embodiment shown in FIG. 4.

As apparent from the above description, a method and apparatus for reformatting a

recording medium according to the present invention can efficiently reformat a specific

management area contained in the recording medium.

Industrial Applicability

It will be apparent to those skilled in the art that various modifications and variations can be

made in the present invention without departing from the spirit or scope of the inventions.

Thus, it is intended that the present invention covers the modifications and variations of this

invention provided they come within the scope of the appended claims and their equivalents.

Claims

[CLAIMS]

1. A method for reformatting a recording medium comprising the steps of:

(a) reading a plurality of physical access control information of the recording

medium in a plurality of recording units; and

(b) performing an initialization process for each recording unit upon receiving a

reformatting command associated with the plurality of recording units, wherein the initialization process is differently performed according to an attribute

of information recorded in each recording unit.

2. The method according to claim 1, wherein the physical access control information of

the recording medium are recorded in a PAC area.

The method according to claim 2, wherein the recording unit is a PAC cluster.

4. The method according to claim 3, further comprising the step of:

(c) if the attribute of the PAC cluster is indicative of a primary PAC, maintaining PAC

status information and PACJD information during a reformatting operation.

5. The method according to claim 3, further comprising the step of: (d) if the attribute of the PAC cluster is indicative of a primary PAC, increasing PAC update

information during a reformatting operation.

6. The method according to claim 3, further comprising the step of:

(e) if the attribute of the PAC cluster is indicative of a non-primary PAC, changing PAC

status information and PACJD information to other information during a reformatting

operation.

7. The method according to claim 6, further comprising the step of:

(f) changing mformation indicative of a valid PAC status to other information indicative of

an available for re-use PAC status during the reformatting operation.

8. The method according to claim 6, further comprising the step of:

(g) changing the PACJD information to other information indicative of a reusable unused

PAC cluster during the reformatting operation.

9. The method according to claim 6, further comprising the step of:

(h) initializing all information contained in the non-primary PAC cluster during the

reformatting operation.

10. A method for reformatting a recording medium comprising the steps of:

(a) recognizing type information of a PAC (Physical Access Control) cluster using PACJD

information contained in each PAC cluster of a PAC area;

(b) if the P AC JD information is indicative of a non-primary PAC cluster, changing PAC

status information and the PACJD information to other information during a reformatting

operation; and

(c) if the PACJD information is indicative of a primary PAC cluster, maintaining the PAC

status information and the PACJD information during the reformatting operation.

11. A method for reformatting a recording medium comprising the steps of:

(a) recognizing type information of a PAC (Physical Access Control) cluster using P AC JD

information contained in each PAC cluster of a PAC area;

(b) if the PACJD information is indicative of a non-primary PAC cluster, changing PAC

operation, and initializing all information contained in the PAC cluster; and

status information and the PACJD information during the reformatting operation.

12. The method according to one of claims 11, further comprising the step of:

(d) if the PACJD information is indicative of the non-primary PAC cluster during the reformatting operation, changing specific information indicative of a valid Pac status to

other information indicative of an available for re-use PAC status.

13. The method according to one of claims 11, further comprising the step of:

(e) if the PACJD information is indicative of the non-primary PAC cluster during the

reformatting operation, changing the PACJD information to other information indicative of

a reusable unused PAC cluster.

14. The method according to claim 11, further comprising the step of:

(f) if the PACJD information is indicative of the non-primary PAC cluster during the

reformatting operation, initializing all information contained in the PAC cluster to a

predetermined initialization value.

15. An apparatus for reformatting a recording medium comprising:

a controller for generating a request for reformatting the'recording medium; and

a recording/reproducing unit for reformatting the recording medium upon receiving the

reformatting request from the controller, recognizing type information of a PAC cluster

using PACJD information contained in each PAC (Physical Access Control) cluster,

changing PAC status information and the PACJD information to other information during

a reformatting operation when the PACJD information is indicative of a non-primary PAC cluster, and maintaining the PAC status information and the PACJD information without

any change during the reformatting operation when the PACJD information is indicative of

a primary PAC cluster.

16. An apparatus for reformatting a recording medium comprising:

a controller for generating a request for reformatting the recording medium; and

initializing PAC status information, the PACJD information, and all information contained

in the PAC cluster during a reformatting operation when the PACJD information is

indicative of a non-primary PAC cluster, and maintaining the PAC status information and

PACJD information is indicative of a primary PAC cluster.

17. The apparatus according to one of claims 16, wherein the recording/reproducing unit

changes specific information indicative of a valid PAC status to other information indicative

of an available for re-use PAC status, if the PACJOD information is indicative of the non-

primary PAC cluster during the reformatting operation.

18. The apparatus according to one of claims 16, wherein the recording/reproducing unit changes the PACJD information to other information indicative of a reusable unused PAC

cluster, if the PAC_ID information is indicative of the non-primary PAC cluster during the

reformatting operation.

19. The apparatus according to claim 16, wherein the recording/reproducing unit initializes

all information contained in the PAC cluster to a predetermined initialization value, if the

PAC D information is indicative of the non-primary PAC cluster during the reformatting

operation.

20. A recording medium acting as an optical recording medium including a data area and a

lead-in area, comprising:

the lead-in area including:

a first management area including a plurality of recording units in which physical access

control information of the data area is recorded, and

a second management area in which recording status information for each recording unit

contained in the first management area is recorded,

wherein the plurality of recording units contained in the first management area are

reformatted according to attribute information of information recorded in each recording

unit.