The PMA sublayer matches the number of PCS lanes to the number of lanes that a physical layer requires. For 40-Gbps transmission, the PMA sublayer maintains four lanes. For 100-Gbps transmission, the PMA sublayer converts 20 lanes to 10 lanes. These sets of lanes are called XLAUI for 40-Gbps and CAUI for 100-Gbps links. (The XL and C stand for 40 and 100 using Roman numerals