mos-filter is the initial task to be run on the data within the esas package for MOS. It calls espfilt to identify good time intervals. Filtering is also done using the standard parameters for PATTERN, etc. mos-filter will process all of the MOS imaging exposures for both detectors for the observation pointed to by $SAS_DIR.
Warning and requirements: mos-filter is part of the esas package integrated into SAS, but it is limited to work within the esas data reduction scheme.