System Use Sharing Protocol
System Use Sharing Protocol (SUSP) is a standard that specifies a uniform way to extend ISO 9660 (CD-ROM) format, to attach arbitrary metadata to each file. It is standardized as IEEE P1281.
Format details
Each ISO 9660 member file has an optional "system use area", whose use is undefined by the ISO 9660 standard. SUSP divides this area into tagged "entries", and defines some standard entry types. Other standards built on SUSP, notably Rock Ridge, define additional entry types. The Wikipedia article for Rock Ridge has a list of entry tags.
Technically, non-core entries are namespaced, using the extension ID string in one or more "ER" entries. Known ID strings:
- "
RRIP 1991A" = Rock Ridge 1.10 - "
IEEE_P1282" = Rock Ridge 1.12
Identification
The known versions of SUSP include the byte sequence 53 50 07 01 be ef. In most cases, this sequence will appear at offset 2048×{the 32-bit little-endian int at offset 32926} + 34.
