x.25
     
         an itu-t standard protocol suite
        for the dte-dce interface in a packet-switched network,
        approved by iso.  x.25 defines standard physical layer,
        data link layer and network layers layers 1 through 3.
        it was developed to describe how data passes into and out of
        public data communications networks.  x.25 networks are in use
        throughout the world.
     
        document: iso 8208.
     
        several other itu-t recommendations are relevant to packet
        switching: x.3, x.28, x.29, x.75.
     
        1996-08-10
     
     
see also:
itu-t standard protocol dte dce packet-switched 
iso physical layer data link layer network layers packet switching 
x.3 x.28 x.29 x.75