  The main themes of this survey are as follows: (a) the canonical
(Riesz--Nevanlinna) factorization in various classes of analytic functions on
the disk that are smooth up to its boundary, and (b) model subspaces (i.e.,
invariant subspaces of the backward shift) in the Hardy spaces $H^p$ and in
BMOA. It is the interrelationship and a peculiar cross-fertilization between
the two topics that we wish to highlight.
