Currently, there seems to be no straightforward way to tell when a Notch block is loading or has finished loading. This is quite important for dynamically-loaded content, especially when exposed parameters need to be handled after the fact.
It would be enough to have the same status channels as the Movie File In TOP and the Audio File In CHOP, namely open, opening and open_failed. Moreover, for dynamically loading Notch blocks it’s commonplace to have an empty file field, which currently makes the operator error out. I think it should have the same behavior as the aforementioned operators in which you only get a warning.