The SCSI family of standards provides for many different transport protocols that define the rules for exchanging information between different SCSI devices. This standard specifies the functional requirements for the Serial Attached SCSI (SAS) physical interconnect@ which is compatible with the Serial ATA physical interconnect. The SAS Protocol Layer (SPL) standard documents the SAS protocol layer corresponding to the Serial Attached SCSI - 2.1 (SAS-2.1) and beyond@ defining the rules for exchanging information between SCSI devices using a serial interconnect. Other SCSI transport protocol standards define the rules for exchanging information between SCSI devices using other interconnects.
INCITS 478-2011 history
2011INCITS 478-2011 Information Technology – Serial Attached SCSI - 2.1 (SAS-2.1)