Interesting but all this defining and explaining leaves my head swimming
so how would you explain this then:
First some credentials: Macauley
Then an article by the writer: Fly Casting Tips | MidCurrent
and lastly note his assessment of overlining about half way down page one.
"Over-Lining a Rod You can make a rod’s action “slower” by overlining the rod with a fly line rated one size higher. "
Also isn't power often used to describe the casting quality of a fly rod and for that matter the fighting power of a particular rod and in both of those cases it isn't just about the lifting power of the rod is it?
The general definition that most rod makers use for power is - the force needed to flex the rod or the rod's resistance to flex. Some rod makers go on to define lifting power, casting power and fighting power.
About the simplest explanation that I've seen that seemingly incorporates all of the above is the Common Cents System and they use another power term, intrinsic power!
The Common Cents System