Public. These contain some useful primitives for manipulating Arpa addresses and determining the address of the running workstation. There are also parsing and printing routines in ConvertExtras at the moment, but eventually they will be moved to Convert.

Buffer structures for the various protocols, as they are passed to clients from deep within the Communication package. I believe these are described in a fairly machine-independent way.

Allows sending and receiving certain ICMP messages. The Arpa echo protocol is based on ICMP, and this interface exists primarily for use by the ArpaICMPEchoTool.

Private interface for use by ICMP, UDP and TCP protocol implementations.

Exports procedures to enumerate the routing table and make queries about routes to hosts or networks. This interface exists primarily for use by the yet-to-be-written ArpaRouterTool.

The Arpa User Datagram Protocol, roughly comparable to the PupSocket and XNSSocket interfaces. There may be good reason to be a client of this interface, and I believe the Mesa source of the interface contains adequate client documentation. Nevertheless, if you can use TCP or SunRPC instead you'll probably be better off.

No user-serviceable parts inside.