By specifying this record in combination with a viscoplastic model
, like group_materi_plasti_visco_power,
a nonlocal yield rule 
will be used in the viscoplastic law.
The nonlocal yield rule needs to be initialized as unknown
by the materi_plasti_f_nonlocal record in the
initialization part.
The nonlocal yield rule in a point is determined by an averaging
of the local yield rule 
in neighbouring points and using
gauss weighting functions for this (i.e. the larger the distance the less
the neighbouring point contributes to the nonlocal yield rule).
The averaging is done over a region with radius nonlocal_radius.
In this way, you can prevent unlimited localization and so mesh dependency, in calculations with softening plasticity.