CQS
From ACT Wiki
Bank supervision.
Credit Quality Step.
A simplified and standardised scale of credit quality, mapped to the credit ratings of the largest credit rating agencies.
The Credit Quality Steps are whole numbers from 1 to 6.
1 is the highest quality, corresponding to ratings of AA- and better in Fitch's and Standard & Poor's (S&P's) ratings.
6 is the lowest quality, corresponding to CCC+ and worse in Fitch's and S&P's ratings.