  Shockwaves in plasma are usually dealt with using Magnetohydrodynamics (MHD).
Yet, MHD entails the assumption of a short mean free path, which is not
fulfilled in a collisionless plasma. Recently, for pair plasmas, we devised a
model allowing to account for kinetic effects within an MHD-like formalism. Its
relies on an estimate of the anisotropy generated when crossing the front, with
a subsequent assessment of the stability of this anisotropy in the downstream.
We solved our model for parallel, perpendicular and switch-on shocks. Here we
bridge between all these cases by treating the problem of an arbitrarily, but
coplanar, oriented magnetic field. Even though the formalism presented is valid
for anisotropic upstream temperatures, only the case of a cold upstream is
solved. We find extra solutions which are not part of the MHD catalog, and a
density jump that is notably less in the quasi parallel, highly magnetized,
regime. Given the complexity of the calculations, this work is mainly devoted
to the presentation of the mathematical aspect of our model. A forthcoming
article will be devoted to the physics of the shocks here defined.
