One statement by Jonathan Holmes in yesterday's MMD about the book
punching machine that he bought mystified me, the one where he said,
"Although it had a new set of punches for keyed music, it unfortunately
did not have a circular punch and die for keyless music."

Admittedly I am a novice when it comes to book music; so I would
appreciate some explanation here.  I understand that a keyed roll frame
needs square-punched holes (square with respect to the hole ends).  But
I thought that a keyless roll frame, being operated pneumatically, not
mechanically, wouldn't care whether the hole punches were round or
square.

What am I missing here?

Matthew Caulfield
Irondequoit, New York