Thin -> Regular
Thin = 0
Light = 0.45
Regular = 0.90, 0.92 (1)

Regular -> Bold
Medium = 0.35
Bold = 0.73, 0.73
Black = 1.125, 1.0


Regular and Black are the only masters with anisotropic interpolation and are used as poles in the var design space. 
Therefore, the Y value of the variation location for named instances would be different than the original fonts.