- You may also be looking for the Richter magnitude scale or the Ritter scale.
The Richter scale of culture was a method of describing cultural achievement in use during the 23rd century.
Prior to learning their true nature, Federation experts rated the Organians at level "D minus" on this scale; presumably, this corresponds to an agrarian culture with hand or animal powered machinery. (TOS: "Errand of Mercy")
In the non-canon TOS novel Prime Directive is indicated which in the early 2200s, Doctor Alonzo Richter invented the Richter scale of culture to monitor a civilization's progress. Several apocryphal sources indicate a classification as show bellow:
AAA : No Known Intelligent Indigenous Life-Forms
AA : Prehistoric Age (No Tools)
AS : Primitive Space Dwelling
A : Stone Age
AR : Primitive ( RESTRICTED - No contact permitted)
B- : Agricultural Age
B : Metal Age
C- : Scientific Intelligence With No Tools
C : Scientific Age
D- : Pre-Industrialization
D : Steam Age
D+ : Electric Age
E- : Liquid Fuels Age
E : Atomic Age
F : Space Age
F+ : Conscientious Space Age
G : Fusion Age
H : Planet Age
I : Star Age
J : Expansion Age
K : Introversion Age
K+ : Enlightenment Age
L : Power Age
M : Ion Age
MR : Ion Age (RESTRICTED - No contact permitted)
N- : Pre-Technocracy Age
N : Technocracy Age
NR : Technocracy Age( RESTRICTED - No contact permitted)
N+ : Civil Technocracy Age
N+PR : Civil Technocracy Age ( RESTRICTED - No physical contact permitted)
NS : Space Dwelling Civil Age
O : Techno-Power Age
P : Super Techno-Power Age
PS : Space Dwelling Super Techno-Power Age
Q : Cloaking Age
R : Exploratory Age
S : Transformation Age
T : Illusory Age
TR : Illusory Age ( RESTRICTED - No contact permitted)
U : Dimensional Age
V : Altering Age
W : Galactic Age
WR : Galactic (RESTRICTED - No Contact Permitted)
X- : Pre-Non-corporeal
X : Non-corporeal Age
XX : High Omnipotence Age