The update_fy3_l1b_calb.c program add additional attribute values to the solar
reflection data in the L1B HDF5 files. In essence it copies the relevant
calibration coefficient values, from the attribute variable VIR_Cal_Coeff, to
the appropriate reflection data sets. 

For example, in the 250m L1B file, the first three elemenents of the
VIR_Cal_Coeff attribute array are:

k2 = VIR_Cal_Coeff [2] * 0.01
k1 = VIR_Cal_Coeff [1] * 0.01
k0 = VIR_Cal_Coeff [0] * 0.01

where p * cos (theta) = k0 + k1 * DN** + k2*(DN**^2) [0]

These two varialbles apply for the first 250m band. For band two the
calculated values are:

k2 = VIR_Cal_Coeff [5] * 0.01
k1 = VIR_Cal_Coeff [4] * 0.01
k0 = VIR_Cal_Coeff [3] * 0.01

[0]: Taken from the MERSI L1 data product user guide, chapter 2. Methods of
calibration.