A single prolate spheroidal element is defined with fibres oriented 65 degrees wrt the horizontal on the inside and -55 degrees wrt the horizontal on the outside. Geometry is interpolated isochorically (Focus^3.Cosh[lambda].Sinh^2[lambda]). Hydrostatic pressure is interpolated quartically in Xi3 (element based) and the pole-zero law defines the incompressible + fluid movement material behaviour. The prolate is inflated with a pressure of 2kPa on the inside face while the the pressure is held at zero on the outside face. The fibre and sheet axis coefficients of the material law are optimised wrt the difference between the calculated nodal forces and the experimentally determined forces (which in this case come from the solution of the boundary value problem in example_544).