Defines the transport layer of the Serial Architecture (SSA). SSA defines a serial interface hierarchy to be used for purposes within its distance and performance characteristics, including, but not limited to, storage subsystems. This standard is intended to be used with an upper layer protocol (e.g., SCSI-2 Protocol (SSA-S2p)) and a physical layer (e.g., SSA Physical Layer 1 (SSA-PH1)). A major goal of the SSA-TL1 standard is to define a transport layer acceptable to vendors, looking for an evolution from parallel SCSI, and systems designers looking for opportunities to more fully exploit the capabilities inherent to a serial bus.