What does "break contact and RTB at your discretion" actually mean?

[Spraug]

When radioing in a contact to higher authorities you either get an attack order or the "information" that other resources will attack the convoy or task force you spotted. The latter entails the statement mentioned above. Since this is a game, I only follow the stand down order when it suits me (in reality you could botch a devastating ambush so of course you should follow the order).

Here's one instance where I found out what it actually means. After a refit in Tulagi, I was ordered to the Bismarck Sea and so I travelled up the Slot and around sunrise encountered a task force of five Fubuki destroyers going NW at maximum speed (so fast I couldn't even correctly estimate their speed but it must have been above 30kn) - Obviously they were part of the Tokyo Express. Attacking five DD is not my idea of fun, so I radioed it in and prayed that I wouldn't get an attack order. Fortunately I got the RTB message and so I stayed submerged and followed them in the periscope to make sure they didn't do anything funny like coming back my way. Suddenly my radar guy picked up multiple very fast radar contacts approaching from the SE. In no time about 15 planes zoomed past and I could see gun fire on the horizon as the Cactus Air Force attacked the task force.

Of course this air attack was set up in the campaign layer and not triggered by my radio message, but I can tell you radioing it in and then picking up the planes sent a shiver down my spine!