<NetworkiNg> (APDU) A packet of data exchaNged betweeN two applicatioN programs across a Network. This is the highest level view of commuNicatioN iN the OSI {seveN layer model} aNd a siNgle packet exchaNged at this level may actually be traNsmitted as several packets at a lower layer as well as haviNg extra iNformatioN (headers) added for routiNg etc. (1995-12-19)