  We present an overview of the temperature, field and angular dependence of
the irreversible magnetization of non-magnetic borocarbides (Y;Lu) Ni_2 B_2 C.
We show that nonlocal electrodynamics influences pinning via the unusual
behavior of the shear modulus in non-hexagonal lattices. On top of that, we
observe that the pinning force density F_p exhibits a rich anisotropic behavior
that sharply contrasts with its small mass anisotropy. When $H \bot c$, F_p is
much larger and has a quite different H dependence, indicating that other
pinning mechanisms are present.
