  We discuss how the redshift (Mattig) method in Friedmann cosmology relates to
dynamical distance indicators based on Newton's gravity (Teerikorpi 2011). It
belongs to the class of indicators where the relevant length inside the system
is the distance itself (in this case the proper metric distance). As the
Friedmann model has Newtonian analogy, its use to infer distances has
instructive similarities to classical dynamical distance indicators. In view of
the theoretical exact linear distance-velocity law, we emphasize that it is
conceptually correct to derive the cosmological distance via the route:
redshift (primarily observed) --> space expansion velocity (not directly
observed) --> metric distance (physical length in "cm"). Important properties
of the proper metric distance are summarized.
