+A slight behavior change is the removal of the -mw option. ``gmx msd`` with ``-mol`` will
+take the MSD of the center-of-mass of of molecules, while no mass-weighting is done
+when ``-mol`` is not selected. In previous |Gromacs| versions, ``-mw`` was on by default,
+and ``-nomw`` was silently ignored when ``-mol`` was chosen. This change will only cause
+different results when performing MSD calculations on a non-homogenous group of particles without
+``-mol`` set.
+