  The notion of a congruence of effective dislocation lines endowed with the
nonvanishing local Burgers vector is introduced. Particularly, the class of
congruences of principal Volterra-type effective dislocation lines associated
with the dislocation densities (tensorial as well as scalar) is distinguished
in order to investigate the geometry of continuized defective crystals in terms
of these densities. It is shown that effective dislocation lines can be endowed
with the dislocation line tension and with a finite self-energy.
