[r-t] Extension (again)

[Richard Smith]

On Saturday, PABS reminded me that I still haven't given him
an example of a method that extends indefinitely, and has
two sensible stages (say on no more than 12 bells), but
where the periodicity of the extension is sufficiently high
that it might be overlooked.

A particularly good example is Spratton Surprise Minor (p.n.
&-3-4-5-3.4-2.5,1).  This has precisely one indefinite
extension: it is 2CD/4FG and works on 8, 20, 32, 44,
56, ... bells.  This is a good example where one might
discover the major extension, discover that the next few
stages don't work, and never find out that it is part of an
indefinite extension series.  This could lead you to believe
that Spratton does not have a legal extension, when in fact
it does.

Another example is Christmas Morning Surprise Minor (p.n
&-5-45-5-3.4-34.5,2).  This time there are two indefinite
extension: 4AB/4FG, which works on 16, 28, 40, 52, ... bells
and 2ABCD/4FG which works on 10, 34, 58, ... bells.  The
latter extension, which has periodicity 24, could easily be
overlooked, leading one to conclude that the royal version
is not a legal extension.

Richard