Gradin Abbreviations used throughout GPA's pricing data

With respects to the notations next to the grades, as per CGC's old label designation for restored/qualified books:

S = Slight
M = Moderate
E = Extensive

A = Amateur
P = Professional

So a combination of SA, would mean Slight Amateur restoration. When A is used on its own it denotes "Apparent" restoration, which simply means a restored label with a specific qualification

Q denotes "Qualified" grade (a green label).

In 2014 CGC introduced a new way of describing restored books:

Slight-A
A-1
Slight/Moderate-A
A-2
Moderate-A
A-3
Moderate/Extensive-A
A-4
Extensive-A
A-5
Slight-B
B-1
Slight/Moderate-B
B-2
Moderate-B
B-3
Moderate/Extensive-B
B-4
Extensive-B
B-5
Slight-C
C-1
Slight/Moderate-C
C-2
Moderate-C
C-3
Moderate/Extensive-C
C-4
Extensive-C
C-5

Additionally, there is now a "C" for "Conserved" books.

You can read further details on the above new restoration grading scale on CGC's website: https://www.cgccomics.com/news/article/4084/