In asynchronous transfer mode (ATM), the specifications for the interface for an ATM endpoint and an ATM switch in a private network, such as an ATMbased LAN. Data Exchange Interface (DXI) is a Private UNI for end-user access to an ATM network from equipment such as a bridge, router, or digital service unit (DSU). See also ATM, ATM reference model, DXI, Public UNI, and UNI.