The following description is taken in part from the technical description manual for the XPRafts software package co-developed by Goyen (1976, 1981, and 1991). The information provides a fairly detailed description of the various modules and procedures within that package that have been utilised in this research.

As the author was the developer of the XPRafts software, the complete source code was obviously available to utilise, modify and build on throughout the current research. The existing overall structure of the XPRafts software provided a very flexible workbench to test an array of process tree type procedures and to view their results.

Within the XPRafts framework the workbench allowed the consideration of linear and non-linear responses, and a mixture of concentrated and distributed storages. The node link structure also allowed the consideration of separately-contributing surfaces with distinctly different infiltration and runoff responses.