Thanks. That helped me start to figure it out. I have X3, and it wasn't obvious to me how to get rid of the Erase box and change it to a Mute (M) box. I also don't exactly have a Help reference section. The help pull down menu leads me to different places, but not a search box. When I finally realized I had to R click on that Erase box to change it to M, and then looked at another site telling me to scroll at the bottom of the track (similar to what I do with audio data,) I was able to scroll thru the MIDI part I wanted to mute.
Thanks very much again.
LNovik