  We analyze the concept of intrinsic radiative gravitational fields defined by
Bel and we show that the three radiative types, N, III and II, correspond with
the three following different physical situations: {\it pure radiation}, {\it
asymptotic pure radiation} and {\it generic} (non pure, non asymptotic pure)
{\it radiation}. We introduce the concept of {\em observer at rest} with
respect to the gravitational field and that of {\em proper super-energy} of the
gravitational field and we show that, for non radiative fields, the minimum
value of the relative super-energy density is the proper super-energy density,
which is acquired by the observers at rest with respect to the field. Several
{\it super-energy inequalities} are also examined.
