Here's some more on the dialup / prestart. it is a completely different animal... The SI's state:

(iv) RRS C4.2 is deleted and replaced with:
“Within the two minute period following her preparatory
signal, a boat shall cross and clear the line between the
entry mark and the Race Committee boat (the Entry Line),
the first time from the course side to the pre-start side. After
that, or after the end of the two minute period following the
preparatory signal, the entry mark no longer ranks as a mark
for the purpose of the definition of a mark”

Here's the diagram