Referenced by a junior office in 2293
Klingon Technical Communication Standards was a book on Klingon communications systems.
In 2293, it was among the books Commander Nyota Uhura and the crew of the USS Enterprise-A referenced to pass themselves off as the Klingon vessel Ursva to a listening post on Morska while violating Klingon space. (Star Trek VI: The Undiscovered Country)