What does R=2N mean?

Question

I'm just wondering what the R=2N means. I guess it's something like "real bar = 2 notated bars," but does anyone know?

Answer 1

Yes, this nomenclature indicates that "one real bar is equivalent to two notated bars."

This is based off of the work of William Caplin, who basically views 8-measure units as the standard lengths in the Classical style. In order to account for lengths that differ from this 8-measure viewpoint, he introduces the distinction between "real" and "notated measures."

Thus a 4-measure phrase is R = 1/2N, because the real measure is only half of the notated measure (and thus the 4-measure phrase is understood as actually being an 8-measure one). This is really common in slower movements.

In contrast, a 16-measure phrase is R = 2N to match the standard 8-measure length; this is common in faster movements.