Quote Originally Posted by NEON View Post
That could be interpreted as if I am asking you to take a look at something. I think that the original and the most appropriate meaning of the twirling finger is to "turn around" and does not necessarily mean "let's exit".

I believe that my interpretation is the one described in the NSS-CDS Cave Diving Manual as well as in the Cave Diving Communications by J.Prosser & H.V.Grey. I suggest that you take a look at the example that J.Prosser uses to illustrate the use of the two signals.
He is right, the "twirly" just means "turn around", not necessarily "exit".