The (x,y) are computed from the CIE tristimulous values (X,Y,Z) as x = X / (X+Y+Z) and y= Y / (X+Y+Z).
You will need the spectral curves for the macbeth checker, as well as the tristimulous curves. You can get that data into your program however you want, but if you want to read the mdla format see the mdl page. Andrew's reformatted data: Andrew's xyz data and Andrew's macbeth data
