The Internet Small Computer System Interface (iSCSI) is a SCSI transport protocol and maps the SCSI architecture and command sets onto TCP/IP. RFC 3720 defines the iSCSI protocol. This document compiles the clarifications to the original protocol definition in RFC 3720 to serve as a companion document for the iSCSI implementers. This document updates RFC 3720 and the text in this document supersedes the text in RFC 3720 when the two differ.