BZ meaning in Military and Defence ?

The combination of the Bravo and Zulu nautical signal flags, i.e., Bravo Zulu, also referred to as "BZ," is a naval signal, typically conveyed by flaghoist or voice radio, meaning "Well Done" with regard to actions, operations or performance. In addition to the British Royal Navy, it has also been used as part of vernacular slang within NATO and other Allied naval forces. It can be combined with the "negative" signal, spoken or written as NEGAT, to say "NEGAT Bravo Zulu" to convey "not well done" for a given action.

"BZ" is widely used as shorthand vernacular amongst members of the sea services. In the Royal Navy, when the sovereign wishes to reward the crew of a British warship with the order to "splice the mainbrace," it is ordinarily followed simply with Bravo Zulu.