This standard describes the framing and signaling interface of a high performance serial link for support of FC-4s associated with upper level protocols (e.g.@ SCSI@ IP@ SBCCS@ VI). This standard is based on FC-FS with subsequent modifications approved by the T11 committee. Extended Link Services (ELSs) are not specified in this standard. FC-LS should be consulted for the functional description of all ELSs referenced in this specification.