S, networking> (UNI) An interface point between ATM end uSerS and a private ATM Switch, or between a private ATM Switch and the public carrier ATM network. The phySical and protocolSpecificationS for UNIS are defined by the ATM Forum' S UNI documentS, which allow for variouS typeS of phySical interfaceS. See alSo: NNI (1999-01-23)