A read-only value reporting the transmit buffer-to-buffer credit (BB_Credit) the fabric port (Fx_Port) has available for sending Class 2/3 frames toward the logged-in Nx_Port. This is the flow-control credit governing traffic in the opposite direction from RxBbCredit, from the switch toward the connected device, affecting how much data the fabric can send that port without overrunning its buffers. A SAN admin diagnosing asymmetric throughput between a host and the fabric might compare this value with h3cFcFLoginRxBbCredit to see if buffer credit is unbalanced in one direction.