Spencer Chase had requested information about the number sequence of
Ampico rolls where the 0-T and 0-B holes were used. It's not easy to
answer that one.
For the popular series, roll 209433, "Did You Mean It," seems to be
close to the first popular B roll that uses the 0-T perforation (1927).
There are a few earlier rolls, such as "The Song Of India," 202491, that
were so popular that American Piano Company reissued them with B coding.
For the ballad series, roll 2001 (1927) seems to be a good starting
point, although they did convert such chestnuts as "Giannina Mia" (1923)
and "The Bells Of St. Mary's" (1923) to B as well.
For the classical series, roll 68091, "By The Waters Of The Minnetonka"
is just about the last A roll produced. There were many earlier rolls
that were converted to the B system. Rachmaninoff, Lhevinne, Schmitz,
Ornstein, and Levitzki were some of the artists who had a great
following during that time, and their rolls were in high demand for the
new B system.
If rolls are in original boxes, it is easier to identify rolls with 0-B
and 0-T holes. Ampico boxes with Art-Deco lettering ninety-nine percent
of the time will contain B-coded rolls. Ampico boxes with stars in the
lower corners usually indicate that the rolls have been issued with B
coding. Ampico rolls with two stars on either side of the title have
been converted to B coding.
This information has been taken from my roll collection and is not the
final word, by any means. I'm sure that there are others out there who
have larger collections with much more experience.