  The slope is an isotopy invariant of colored links with a distinguished
component, initially introduced by the authors to describe an extra correction
term in the computation of the signature of the splice. It appeared to be
closely related to several classical invariants, such as the Conway potential
function or the Kojima eta-function (defined for two-components links). In this
paper, we prove that the slope is invariant under colored concordance of links.
Besides, we present a formula to compute the slope in terms of C-complexes and
generalized Seifert forms.
