The Fluxgate-Searchcoil Merged (FSM) data product for the Magnetospheric
Multiscale (MMS) mission is created by combining the level-2 science quality
data from the fluxgate and searchcoil magnetometers into a single level-3 data
product. The merging method involves noise floor and calibration parameters
determined both on the pre- and post-flight. Here, we describe the statistical
inter-calibration process as well as the merging filter.