This is a software constructed FIS. For data transfer operations, this is the H2D Register FIS format as specified in below sections. The HBA sets PxTFD [STS_BSY], and then sends this structure to the attached port. If a port multiplier is attached, this field must have the port multiplier port number in the FIS itself – it should not be added by the HBA. Valid CFIS lengths are 2 to 16 Dwords and must be in Dword granularity.