ACKNOWLEDGE: Let me know that you have received and understand this message
AFFIRM: Yes
APPROVED: Permission for proposed action approved
BREAK: I hereby indicate the separation between portions of the message (To be used where there is no distinction between the text and other portions of the message).
BREAK BREAK: I hereby indicate the separation between messages transmitted to different aircraft in a very busy environment
CANCEL: Annul the previously transmitted message
CHECK: Examine a system or procedure. (No answer is normally expected)
CLEARED: Authorized to proceed under the conditions specified.
CONFIRM: Have I correctly received the following......? or did you correctly receive this message?
CONTACT: Establish radio contact with........
CORRECT: That is correct.
CORRECTION: An error has been made in this transmission (or message indicated) the correct version is........
DISREGARD: Consider that transmission as not sent
GO AHEAD: Proceed with your message.