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.
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.