To help ensure the proper operation of NCIC, the standards, procedures, formats, and criteria presented in this manual must be strictly followed. Control terminals must not only follow the rules presented but must also ensure the agencies they are servicing do the same. There are six types of messages that originate with a terminal and can be transmitted to the NCIC computer. These messages pertain to NCIC records and are entry, modification, cancellation, inquiry, locate, and clear. The three types of messages that originate from NCIC are acknowledgment messages, inquiry responses, and administrative messages. Procedures for the six types of messages are discussed for the following NCIC files: vehicle, license plate, boat, gun, article, securities, wanted person, missing person, Canadian warrant, and criminal history. A subject index is provided.