no duff

Etymology
From the RAF slang expression "duff gen" meaning bad information; no duff, by extension means accurate, also: stop operations until ordered otherwise.

Noun

 * 1)  An incident that is not a drill or training exercise; an emergency. Also end of exercise. Stop drill immediately. As a ‘tap out’ called by during physical training. Sim munitions training in Australian Swat ‘end ex’.
 * 2) * 2003, “Jordie Yeo: Master Corporal” in John Wood ed., The Chance of War: Canadian Soldiers in the Balkans, 1992–1995, Dundurn Press:
 * [p 224] I called on the radio and — this was the most horrifying part of this — I couldn’t reach my observation post where my guys were. But I did get the command post in the middle of Srebrenica. I told them, “This is a no duff situation. You’ve got two men down and we’re on the trail.’
 * [p 236, glossary] No duff The radio code words used to get people off the air because a serious incident has occurred.
 * [p 236, glossary] No duff The radio code words used to get people off the air because a serious incident has occurred.