The TDR meters have 2 modes of operation, volumetric water content (VWC) and relative water content (RWC).  In RWC mode, soil moisture is reported on a scale of 0 - 100 with the low and high moisture levels configured by the user.  The TDR meters can support 5 different RWC ranges.   RWC values are computed from the measured VWC measured by the meter.  Pressing the MODE button allows the user to scroll between the 6 different mode options.