Modify Timecode Offset


In a tutorial on writing music for picture, I saw that you could shift the start time of the movie. So, I shifted the start time to bar two, and marked that position as 00:00:00;00. I then get this message, “You have modified the timecode offset. Do you want to keep the project content at its present timecode position? Yes - No?”

What are the implications of either?

I RTFMed, but any reference or explanation available is vague.

Does anyone here know?