I think the "O" roll was started around 1910 by Operators Piano Co.
and was used only by pianos made by the Operators Piano Co.  These
would include Coinola Brand, Empress Electric, and one made under the
Welte Multitone name.

Most "O" rolls were produced by Operators using the Capitol Roll &
Record Co. name in later years.  The earliest rolls by Operators were
sold under the Columbia Music Roll Co. name.  I think the name change
came about 1920 or so with the popularity of the Columbia Phonograph
(no relation) name, forcing Operators to change their roll name from
Columbia to Capitol.  Clark Roll company also issued a few "O" rolls.
Play-Rite Music Rolls brand is the company founded in the 1960s that
recuts old rolls and has made some new style "O" rolls.

Don Teach - Shreveport Music Co.
Shreveport, Louisiana

 [ A short history of Columbia Music Roll Co. / Capitol Roll & Record Co.
 [ by Mike Montgomery is at http://www.mmdigest.com/Gallery/MMMedia/CoCap 
 [ and illustrations of most Coinola nickelodeons are at
 [ http://www.mmdigest.com/Gallery/Pictures/Coinola/coinola_cards.html 
 [ -- Robbie