SES-2 Enclosure Management
The introduction of Serial Attached SCSI (SAS) as the most recent evolution of SCSI required redefining the related standard for enclosure management, called SCSI Enclosure Services. SES-2, or SCSI Enclosure Management 2 first revision, was introduced in 2002 and is now at revision 20.
Source: Wikipedia — SES-2 Enclosure Management (CC BY-SA 4.0)