I'm sorry to contradict you Mitch but most MIDI guidelines suggest not using 7 Main Volume for periodic changes of volume throughout the song but rather to use controller 11 Expression instead.

The main reason for this is if you set Main Volume only once at the beginning of the song then if you decide to change it you only have to change it in one place. All the Expression values throughout the song will then behave in response to the Main Volume change.

Regards

Richard Williams
Sydney
Australia