Reference essential genes for Chronos score scaling

What genes are used as reference essential genes to scale the DepMap Chronos gene effect scores?
Is it the genes listed in AchillesCommonEssentialControls.csv or CRISPRInferredCommonEssentials.csv?

It’s the AchillesCommonEssentialControls. CRISPRInferredCommonEssentials are the genes determined to be common essential from the screens themselves.