Mean line-spread function of the MILES library, using for reference (i) the interpolated ELODIE spectra (red line and symbols); and (ii) the ELODIE spectra of stars in common (green). The top panel gives the mean residual shift over all the library, and the bottom panel the mean FWHM wavelength resolution. The bars indicate the errors on the mean value (i.e. dispersion/). The abscissa of the red symbols are shifted by a small quantity to avoid superposition.