5.1 Hosts and hubs

     The coordinator of a net is called the host or NC for Network
     Coordinator. The host is responsible for maintaining the nodelist
     segment for his/her net and to act as an inbound NetMail gateway
     for the systems in his/her net ("host routed mail").

     In a large net, it is quite common that "sub-hosts", called hubs,
     are set-up to aid in mail distribution within the net. In other
     words, a hub has the same function for systems in a network that
     a host has for (remote) systems outside the same network.