R M value in planar chromatography

https://dx.doi.org/10.1351/goldbook.R05022
A logarithmic function of the R F value (retardation factor):
R M = log 10 ( 1 − R F R F ) = log 10 ( 1 R F − 1 )
Source:
PAC, 1993, 65, 819 (Nomenclature for chromatography (IUPAC Recommendations 1993)) on page 845