The use of a system for on-line conversation in ordinary English grammatical patterns is illustrated by a number of examples showing how data bases of diverse content and structure may be described, interrogated, and modified. It is suggested that a system composed of a user extendable subset of English, a natural language compiler to translate the English sentences into storage and search procedures, and a data management machine to execute these procedures, can provide an on-line user with a natural, easy-to-use, and powerful means of man-to-machine communication. (Author)