The function magmax can easily be updated to get more accurate results by plugging in another SN spectrum than the one currently used. It is also very easy to plug new filters in. In both cases, the C program norm_filter (source code norm_filter.c) hast to be used for finding the calibration of the new SN spectrum or the new filters. The way the source code of norm_filter has to be changed is very similar to the way the source code of magnitude.so (magnitude.c) has to be changed. Actually, magnitude.c was developed out of the source code of norm_filter.c The section 2.6.1 below describes the calibration process, the section 2.6.2 describes how to change the source code of magnitude.so For updating magnitude.c in this way it is necessary that the calibration is already known.