10 Gigabit Attachment Unit Interface (XAUI /ˈzaʊi/ ZOW-ee) is a standard for extending the XGMII (10 Gigabit Media Independent Interface) between the MAC and PHY layer of 10 Gigabit Ethernet (10GbE) defined in Clause 47 of the IEEE 802.3 standard. The name is a concatenation of the Roman numeral X, meaning ten, and the initials of 'Attachment Unit Interface'. 10 Gigabit Attachment Unit Interface (XAUI /ˈzaʊi/ ZOW-ee) is a standard for extending the XGMII (10 Gigabit Media Independent Interface) between the MAC and PHY layer of 10 Gigabit Ethernet (10GbE) defined in Clause 47 of the IEEE 802.3 standard. The name is a concatenation of the Roman numeral X, meaning ten, and the initials of 'Attachment Unit Interface'.