Is R for Regular or Rigid?

Equipment
1

I remember reading somewhere the manufacturers used an R on the shaft for rigid back in the day.
I don’t seem to be able to figure out how to search this site properly to find the info.
Does anyone know which manufacturer and what years?
If so, is a rigid shaft stiffer than a S shaft back then?
Thanks!

2

In early 50’s Mac’s, R was “rigid” and V was “firm/regular”. Then they got into numbering: 1 for stiff, 2 for firm/reg, etc. In general, the older stuff will run stiffer than a comparable modern shaft. “Stiff” shafts from the 50’s and 60’s were VERY stiff.

3

[b]Shafts

Woods
True Temper 1950 thru 1957[/b]
C - Stiff
D - Medium/Stiff
E - Medium
G- Ladies or Juniors
K - ?

Irons
True Temper (from a 1954 ad)
R chrome shafts - Medium-Stiff
V chrome shafts - Firm, Medium-Stiff
Y - Ladies
Z - Seniors
Meteor - Ladies
Century - Junior

Propel 1958 thru 1968
#1 - Still
#2 - Medium/Stiff
#3 - Medium/Soft
#4 - Soft

A - Aluminium
Rocket L shaft “for players who prefer more flex”