  We use the Blanchfield-Duval form to define complete invariants for the
cobordism group C_{2q-1}(F_\mu) of (2q-1)-dimensional \mu-component boundary
links (for q\geq2).
  The author solved the same problem in math.AT/0110249 via Seifert forms.
Although Seifert forms are convenient in explicit computations, the
Blanchfield-Duval form is more intrinsic and appears naturally in homology
surgery theory.
  The free cover of the complement of a link is constructed by pasting together
infinitely many copies of the complement of a \mu-component Seifert surface. We
prove that the algebraic analogue of this construction, a functor denoted B,
identifies the author's earlier invariants with those defined here. We show
that B is equivalent to a universal localization of categories and describe the
structure of the modules sent to zero. Taking coefficients in a semi-simple
Artinian ring, we deduce that the Witt group of Seifert forms is isomorphic to
the Witt group of Blanchfield-Duval forms.
