Late last century a friend of mine was working in the public service in Canberra.
Specifically he was working in the Department of Defence, though somewhat unhappily. One day he showed me an internal mail bag marked Defence Signals Directorate.
It didn't mean anything to me, so he explained that the Signals Directorate were a secretive part of the Australian military that were often unacknowledged as their role was intercepting foreign communications.
These days they're better known, particularly after the 2013 news they had overheard conversations between then Indonesian president Susilo Bambang Yudhoyono and his wife.
Funny thing was that as soon as I got the screenshot it vanished from beside my news feed.