The M906 setting in RRF is the peak current per phase.
Note, this may not be the same as Marlin, because Marlin uses either peak current or RMS current, depending on which fork and which driver chips are in use. RepRapFirmware supported setting motor currents well before Marlin did, and at that time it was normal to refer to peak motor current per phase in 3D printer discussions. So RRF has stuck with peak current per phase to be consistent.