I'm new to this website and have one big question: what do all those
holes in piano rolls and books mean?  I read music and my background
is 30+ years as a computer systems programmer.  I understand the basic
process, i.e., a hole means to play a note.  What do they all mean,
from the first hole on a roll to the last.  If there are any good books
available, I'd appreciate that, too.  Please advise.

Ron Williams