Flattened stellar systems based on distribution functions depending on
  actions
  We address an issue that arises when self-consistently flattened dynamical
stellar systems are constructed by adopting a distribution function (DF) that
depends on the action integrals. The velocity distribution at points on the
symmetry axis is controlled by the the dependence of the DF on just one action,
while at points off the symmetry axis two actions are involved. Consequently,
the physical requirement that the velocity distribution evolves continuously in
the neighbourhood of the symmetry axis restricts the functional forms of
acceptable DFs. An algorithm for conforming to this restriction is presented
and used to construct a variety of flattened models.
