This International Standardized Profile is applicable to interworking units concerned with operating in the Open Systems Interconnection (OSI) environment. It specifies a combination of OSI Base standards that collectively provide a Network Relay function for the connectionless-mode Network Service. This part of ISO/IEC ISP 10613 specifies media-dependent requirements which are applicable to an interworking unit attached to an ISO/IEC 8802-3 CSMA/CD LAN subnetwork. The operation of an interworking unit may involve relaying from one subnetwork to another, and those subnetworks need not be of the same type. This part of ISO/IEC ISP 10613 applies only to communication over those subnetworks which are ISO/IEC 8802-3 CSMA/CD LANs.