Julian Dyer asks:

> Is there any good proof (such as trade journals) which offers better
> data about precisely when the formats were introduced and withdrawn?

I would think that circa 1911 is the magic date, because in Feb, 1911,
a Music Roll Standard was adopted by the industry.  In this, 9 holes-
per-inch was set as the standard.

See MMD from Jan 13, 1998, "1911 American Music Roll Standards," for
all the nitty gritty details of the standard, taken from the AMICA
Bulletin (v34, #6, 1997)..

Rick Inzero, Rochester, NY, rdi@cci.com