Re: Fly rod line rating, power, and action - an explanation.
I see no mention here of anything but a progressive taper. Before the advent of fiber reinforced plastic (FRP) rods - glass, graphite, and boron - the split cane rods were created with many different casting tapers.
One of the favorite tapers among cane rodmakers today is what is known as a "parabolic taper" or "semi-parabolic taper". Many rodmakers of "the Golden Age" designed with a gentle version of the parabolic taper. The original parabolic was probably the Castleconnell Kick rod; which acted as described - the butt would start the cast, a more limber mid-section would cause delay, and then throw the relatively stiff tip section over quickly. Inelegant, but very good for heaving out lots of line for salmon.
With a cane rod you have a significant amount of mass that is lacking in an FRP rod. This allows for more varied casting strokes. For example, with a 10' "wet fly action" (straight taper) the tip has appreciable mass. [ many wet fly rods were lighter on the scales than a dry fly rod of the same length, but they felt tip-heavy.] So, it is possible to simply bend the wrist - no arm movement required - and watch the tip load to the mid. On the forward cast the tip will - depending on the rod - actually stay in line with the line as it shoots, before straightening. This allowed for fewer false casts (false casts dried the fly you wanted to sink). To perform an upstream mend when the line was already on the water, you could just roll your hand and the mass of the tip would flip the line over.
Just some thoughts. YMMV