  The gravitational lensing equations for convergence, potential, shear, and
flexion are simple in polar coordinates and separate under a multipole
expansion once the shear and flexion spinors are rotated into a ``tangential''
basis. We use this to investigate whether the useful monopole aperture-mass
shear formulae generalize to all multipoles and to flexions. We re-derive the
result of Schneider and Bartelmann that the shear multipole m at radius R is
completely determined by the mass multipole at R, plus specific moments Q^m_in
and Q^m_out of the mass multipoles internal and external, respectively, to R.
The m>=0 multipoles are independent of Q_out. But in contrast to the monopole,
the m<0 multipoles are independent of Q_in. These internal and external mass
moments can be determined by shear (and/or flexion) data on the complementary
portion of the plane, which has practical implications for lens modelling. We
find that the ease of E/B separation in the monopole aperture moments does {\em
not} generalize to m!=0: the internal monopole moment is the {\em only}
non-local E/B discriminant available from lensing observations. We have also
not found practical local E/B discriminants beyond the monopole, though they
could exist. We show also that the use of weak-lensing data to constrain a
constant shear term near a strong-lensing system is impractical without strong
prior constraints on the neighboring mass distribution.
