Abstract
LADDER (Language Access to Distributed Data with Error Recovery) is a computer system designed to provide answers to questions posed at the terminal in a subset of natural language regarding a distributed data base of naval command and control information. The system accepts a fairly wide range of natural-language questions about the data. For each question LADDER plans a sequence of appropriate queries to the data base management system, determines on which machine the queries are to be processed, establishes links to those machines over the Arpanet, monitors the processing of the queries and recovers from certain errors in execution, and prepares a relevant answer to the original question. The users guide is intended for the person who knows how to log in to the host operating system, as well as how to enter and edit a line of text. It does not explain how LADDER works, but rather how to use it on a demonstration basis.