  In this paper, we introduce super Weyl groups, their distinguished elements
and properties for basic classical Lie superalgebras. Then we formulate Jantzen
filtration for baby Verma modules in graded restricted module categories of
basic classical Lie superalgebras over an algebraically closed field of odd
characteristic, and prove a sum formula in the corresponding Grothendieck
groups. We finally obtain a strong linkage principle in such categories.
