This section describes a facility that provides most of the logical advantages of centralized processing in a distributed processing environment. Section (p2,tymnet) discusses the connection of a program to a Tymnet circuit; this section discusses connections of programs running in remote computer systems that may not need to be aware that their correspondents are remote. Section (p2,pubdirec) describes publicly available directories that can serve to establish gates between programs. As described it could only connect programs running in "the same Gnosis". A more complex form of public directory called a (_mail union), has foreign connections with similar programs at other sites. This connection is presumably made using the facilities described in section (p2,tymnet).
A mail union is thus a set of programs at distinct sites. These programs are in communication with each other and in league to provide the illusion that there is but one site. When a member <NAME, KEY> is added at one site NAME appears immediately at each site along with a notation as to which site KEY is at. If KEY is an entry key and R is a site that is remote from KEY and a program at R asks for NAME the mail union program constructs an entry key KEYR that leads to code that will cause KEYR at R to behave like KEY. KEYR will be handed out at R when NAME is asked for.