CD001 - сигнатура (маленькая часть) заголовка (volume descriptor'а). В общем - если ее нет, то это мусор. Заголовок вот:
typedef unsigned char Byte;
typedef unsigned short Word;
typedef unsigned long Long;
typedef struct
{
Byte VDType; /* Must be 1 for primary volume
descriptor. */
char VSStdId[5]; /* Must be "CD001". */
Byte VSStdVersion; /* Must be 1. */
Byte volumeFlags; /* 0 in primary volume
descriptor. */
char systemIdentifier[32]; /* What system this CD-ROM is
meant for. */
char volumeIdentifier[32]; /* The volume name. */
char Reserved2[8]; /* Must be 0's. */
Long lsbVolumeSpaceSize; /* Volume size, least-significant
-byte order. */
Long msbVolumeSpaceSize; /* Volume size, most-significant
-byte order. */
char escapeSequences[32]; /* 0's in primary volume
descriptor */
Word lsbVolumeSetSize; /* Number of volumes in volume
set (must be 1). */
Word msbVolumeSetSize;
Word lsbVolumeSetSequenceNumber;/* Which volume in volume set
(not used). */
Word msbVolumeSetSequenceNumber;
Word lsbLogicalBlockSize; /* We'll assume 2048 for block
size. */
Word msbLogicalBlockSize;
Long lsbPathTableSize; /* How many bytes in path
table. */
Long msbPathTableSize;
Long lsbPathTable1; /* Mandatory occurrence. */
Long lsbPathTable2; /* Optional occurrence. */
Long msbPathTable1; /* Mandatory occurrence. */
Long msbPathTable2; /* Optional occurrence. */
char rootDirectoryRecord[34]; /* Duplicate root
directory entry. */
char volumeSetIdentifier[128]; /* Various copyright and
control fields follow. */
char publisherIdentifier[128];
char dataPreparerIdentifier[128];
char applicationIdentifier[128];
char copyrightFileIdentifier[37];
char abstractFileIdentifier[37];
char bibliographicFileIdentifier[37];
char volumeCreation[17];
char volumeModification[17];
char volumeExpiration[17];
char volumeEffective[17];
char FileStructureStandardVersion;
char Reserved4; /* Must be 0. */
char ApplicationUse[512];
char FutureStandardization[653];
} PVD, *PVDPtr;
CD001 - сигнатура (маленькая часть) заголовка (volume descriptor'а). В общем - если ее нет, то это мусор. Заголовок вот:
typedef unsigned char Byte; typedef unsigned short Word; typedef unsigned long Long; typedef struct { Byte VDType; /* Must be 1 for primary volume descriptor. */ char VSStdId[5]; /* Must be "CD001". */ Byte VSStdVersion; /* Must be 1. */ Byte volumeFlags; /* 0 in primary volume descriptor. */ char systemIdentifier[32]; /* What system this CD-ROM is meant for. */ char volumeIdentifier[32]; /* The volume name. */ char Reserved2[8]; /* Must be 0's. */ Long lsbVolumeSpaceSize; /* Volume size, least-significant -byte order. */ Long msbVolumeSpaceSize; /* Volume size, most-significant -byte order. */ char escapeSequences[32]; /* 0's in primary volume descriptor */ Word lsbVolumeSetSize; /* Number of volumes in volume set (must be 1). */ Word msbVolumeSetSize; Word lsbVolumeSetSequenceNumber;/* Which volume in volume set (not used). */ Word msbVolumeSetSequenceNumber; Word lsbLogicalBlockSize; /* We'll assume 2048 for block size. */ Word msbLogicalBlockSize; Long lsbPathTableSize; /* How many bytes in path table. */ Long msbPathTableSize; Long lsbPathTable1; /* Mandatory occurrence. */ Long lsbPathTable2; /* Optional occurrence. */ Long msbPathTable1; /* Mandatory occurrence. */ Long msbPathTable2; /* Optional occurrence. */ char rootDirectoryRecord[34]; /* Duplicate root directory entry. */ char volumeSetIdentifier[128]; /* Various copyright and control fields follow. */ char publisherIdentifier[128]; char dataPreparerIdentifier[128]; char applicationIdentifier[128]; char copyrightFileIdentifier[37]; char abstractFileIdentifier[37]; char bibliographicFileIdentifier[37]; char volumeCreation[17]; char volumeModification[17]; char volumeExpiration[17]; char volumeEffective[17]; char FileStructureStandardVersion; char Reserved4; /* Must be 0. */ char ApplicationUse[512]; char FutureStandardization[653]; } PVD, *PVDPtr;