The calibration is based in the identification of spectral features in the observed spectra of F-type stars for the UV grism and BPM 16274 for the Visible one.
A polynomial (degree 2 for UV and 1 for Visible) is used to fit the laboratory wavelengths as a function of the pixel number counted from the centroid of the zero order. The CCF table is obtained by applying the polynomial to a monotonic array representing the pixels array in the extracted spectrum.