Abbreviations: IOU and JIT

[Nicole]

Hi, in an English level assessment test I have come across these two abbreviations:
JIT and IOU. I hadn't seen them before, according to acronymfinder they can mean 'Just In Time' and 'I Owe You'. (there are many other possible meanings). Now, my question is how common are those two abbreviations in business? I mean, acronyms or abbreviations like a.s.a.p. and CEO or often used in business correspondence. I'm not so sure about JIT and IOU though.
Thanks in advance. As ever.
Nicole

PS: Is there a difference between thanks in advance and thanks beforehand?
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Life is for living.

[Jamie (K)]

[Andreana]

Hello Jamie (K)! Your explanations are very interesting, thank you for sharing your knowledge with us. Incidentally, I've checked the word promisory note and it occurs that it spelled like with two s: promissory note.
Regards
Andreana
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[Jamie (K)]