A History of U.S. Communications Security; the David G. Boak Lectures, National Security Agency (NSA), Volumes I, 1973, partially released 2008, additional portions declassified October 14, 2015, p. 37, Quote: The KL-7 “was our first machine designed to serve very large nets which could stand matched plain and cipher text. For the first time, the man in the cryptocenter could take a message and simply type it into the machine as written, without changing the spacing between words, or cutting the message in half and sending the last part first. and without having to paraphrase the message text before it was released.”
