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-2 (ISO/IEC 14165-252) with subsequent modifications approved by the member body that originally authored and approved FC-FS-2. The following Fibre Channel features specified in FC-FS-2 are obsolete in this standard: Feature Alias service Association_Header Class 1 service Class 6 service Connections Continue Sequence Condition F_CTL bit Discard multiple Sequences with immediate retransmission Hunt Group Intermix Multicast service Preemption Quality of Service Facilitator Retransmitted Sequence F_CTL bit Stacked Connect