  In the continuum theory the time evolution of surfaces eroded by ion
bombardment is modelled by stochastic partial differential equations (SPDEs).
These determine the scaling regimes and universality classes of the evolving
surfaces. Current knowledge of these scaling regimes is based on the existing
continuum theory calculations of topographic phase diagrams as functions of the
sputtering parameters, which is limited to small values and isotropic cases of
the sputtering parameters. And which accounts mainly for ripple patterns and
rough surfaces. Recent work has demonstrated the existence of non-ripple
nanostructures for anisotropic collision cascade parameters not considered in
the existing continuum theory analysis of possible scaling regimes of sputtered
surfaces. In this work we calculate phase diagrams representative of a wider
range of sputtering conditions, with anisotropic collision cascading in
general. The results reveal new scaling regimes yet unaccounted for. The
results also reveal a possibility of modelling a wide range of materials with
the same SPDE for {\theta} \leq 30{\deg} thus indicating an important
universality class.
