In libraw_colordata_t, there is a variable called FujiExpoMidPointShift. I couldn't find any documentation about it. FujiExpoMidPointShift seems to contain the "Raw Exposure Bias" value shown in Exiftool. Could you explain how to use it?

DNG files contain a BaselineExposure value written by Adobe. I examined several Fuji raw files and their corresponding DNG files. In some raw files I have, LibRaw's FujiExpoMidPointShift is always -2.72 but the DNG's BaselineExposure is 2.15 and 2.51 depending on the ISO. In other raw files, FujiExpoMidPointShift is -0.72 and BaselineExposure is 0.15. Is there a way to convert between FujiExpoMidPointShift and BaselineExposure?