4. The topic-interpreting method in accordance with claim 3 which comprises in addition the steps of limiting execution of said at least one transfer command, in terms of extent of transfer, by marking an end of transfer through said database by at least one predetermined marking flag in said database, said marking flag being either the same as or different from one of said announce flags, and executing said one transfer command by searching said database for said marking flag from a topic location, at which said routine was called, in a direction determined by such command.
4. The topic-interpreting method in accordance with claim 3 which comprises in addition the steps of limiting execution of said at least one transfer command, in terms of extent of transfer, by marking an end of transfer through said database by at least one predetermined marking flag in said database, said marking flag being either the same as or different from one of said announce flags, and executing said one transfer command by searching said database for said marking flag from a topic location, at which said routine was called, in a direction determined by such command. 6. The topic-interpreting method in accordance with claim 4 in which a stack is provided in memory for topic definitions, each including at least a control flag field, a topic definition for at least one topic includes a binary quit flag, said one transfer command is a quitting command, and said executing step for said quitting command includes the steps of searching said control flag fields in said stack for a marking flag in the form of a quit flag in a set state, and resuming delivery of said material at a topic definition having said set quit flag.