A defining equation to describe the moments of the surface concentration-eroded depth profile of a marker species during sputter erosion, in the framework of ion bombardment enhanced diffusivity and which includes the process of ion penetration and trapping, is developed. Simplified trapping profiles illustrate the effect of this process in modifying profile moments. Estimates of large erosion depth quasi-exponential decay lengths are also made and, again, the role of ion trapping is elucidated. It is concluded that experimental measurements of these profile parameters (particularly the profile moments for which analysis is rigorous and exact) should be preferably compared with the results developed in this work rather than with previous treatments. The exceptions to this proposal are either when the sputtering yield is much larger than the total ion trapping probability, so that substrate dilation or compression can be ignored, or when it can be definitely assumed that the characteristic length of the diffusion process is much larger than the depth over which diffusion enhancement occurs.