I noticed, per the ICC specs, that A2Bx tags include a '3x3 matrix' which is
mostly an "identity" matrix, where the diagonals are equal to 1.0. Page 66
of the Specs ICC1 v43_2010 states :
Each matrix entry is encoded as an s15Fixed16Number.colour space.
The domain and range of the matrix is 0,0 to 1,0.
The matrix shall be an identity matrix unless the input is in the PCSXYZ