  The analytic structure of the S-matrix of singular quantum mechanics is
examined within a multichannel framework, with primary focus on its dependence
with respect to a parameter ($\Omega$) that determines the boundary conditions.
Specifically, a characterization is given in terms of salient mathematical and
physical properties governing its behavior. These properties involve unitarity
and associated current-conserving Wronskian relations, time-reversal
invariance, and Blaschke factorization. The approach leads to an interpretation
of effective nonunitary solutions in singular quantum mechanics and their
determination from the unitary family.
