Data processing of the multi-object fiber spectra

With data obtained by the multi-object fiber spectrograph (MOFS) of the Russian SAO 6-meter telescope, the general procedures of observation and data processing of the MOFS spectra are described. The main error sources are analyzed. Towards a better sky subtraction, factors such as scattered light, relative fiber transmittance, wavelength and flux calibrations are discussed and modifications suggested according to the conditions of the instruments and software.