Extended objects such as line or surface operators, interfaces or boundaries
play an important role in conformal field theory. Here I propose a systematic
approach to the relevant conformal blocks which are argued to coincide with the
wave functions of an integrable multi-particle Calogero-Sutherland problem. This
generalizes a recent observation in the literature. Applications range from
several new relations with scalar four-point blocks to a Euclidean inversion
formula for defect correlators.
