physical medium (PM)
The physical media for ATM deployment refers to the current physical interfaces. There are a variety of defined interfaces: STS-1, STS-3c, STS-12c, STM-1, and DS transmission interfaces DS-1, DS-2, DS-3, and E transmission interfaces E-1, E-3, and E-4, in addition to FDDI-based, Fibre Channel-based, and STP interfaces.