Original SDSS transmission curves from Doi et al. (2010, black dashed line) are compared to their tweaked version obtained with the standardisation process (green continuous lines). It is important to remember that the shape of standardised TCs is designed to correct for the systematic errors that still affect EC XP spectra. No tweaking is applied to the u passband, as the standardisation of u magnitudes and fluxes is performed by means of polynomial transformation. The cut at 330 nm follows the TC of the BP spectrometer.