When a general user is introduced to the system he is given his own directory. In that directory he may find a key to an (_interchange directory). Such an entry is good for depositing some limited number of members in the associated directory. Members of such a directory are an association between a name and a key. Anyone with a key to that interchange directory may acquire a copy of a key in the directory by presenting the name associated by the directory with the key. CD(11,((1,LN),(LN,NAME));==>c,S;E) returns the key associated with NAME. If c is 0 there was such a key. If c is 1 there was none. S, if it exists, may be an EBCDIC description of a person suitable for verifying who will receive the mail.

To deposit a key in the directory do CD(6,((1,LN),(LN,NAME), (1,LS),(LS,S));E ==>c;). This associates NAME with E and returns 0 if NAME was not in use but returns 3 otherwise. c will be 5 if the quota was exceeded. CD(15,((1,LN),(LN,NAME);==>c,S;K) deletes the name NAME but the same entry must be used as was used to enter the name.

A particular community interchange directory called MAIL is provided with the convention that one register his mail receiver in MAIL soon after he is introduced to the system. To send a segment to Mephisto do MAIL(0,'Mephisto';==>c;E). If c=1 this directory knows no one by this name. Otherwise do E(0,segment_name;SEG==>c;RETSEG) and Mephisto's mail receiver will have the opportunity to stash SEG in a place where Mephisto will be able to access it. "segment_name" is provided for additional information to the mail receiver.

Some keys found in the interchange directory may not be prompt. In fact some may be designed to return when a person has prepared a reply to the mail. In this case the convention is to return a segment key with the reply. Note that this convention permits contacting someone anonymously with provisions for exactly one reply from that person. {He can't put you on a mailing list.}