Oh neat find! So yes, I use “//“ to separate an action from notes for that action in OmniFocus. So if there is a line like:
– [ ] Call the auto shop to arrange repair // Ask for Sally
… then the action of “Call the auto shop” will be created in OmniFocus with a note of “Ask for Sally”.
I don’t really use it as much as I thought I would, but it wasn’t worth the work to take it out. Maybe it’s useful for you, though!