Are bearing signals operational? If so, how?
 

I'm using The Wolves of Steel if that matters, but usually when I send a contact report of a convoy and the BDU dispatches all nearby submarines, they start asking me for a bearing signal. Is this implemented? Is there some way I can send this signal out? I can't find any way to do this. The same exists for the flip side when I'm told to assist a submarine with an attack and it says they are sending a bearing signal, I have no idea how to actually receive it and know where they are