Bootable CD-ROM Format Specification

Version 1.0 Copyright  1994 Phoenix Technologies and IBM All Rights Reserved. Page 13
Offset Type Description
0 Byte Boot Record Indicator, must be 0
1-5 Byte ISO-9660 Identifier, must be “CD001”
6 Byte Version of this descriptor, must be 1
7-26 Byte Boot System Identifier, must be “EL TORITO SPECIFICATION” padded
with 0’s.
27-46 Byte Unused, must be 0.
47-4A Dword Absolute pointer to first sector of Boot Catalog.
4A-7FF Byte Unused, must be 0.
Figure 7 - Boot Record Volume Descriptor