The code computes secondary compression volumetric strain rate as a function of distance from the normal consolidation line in e-log(sigma_v’) space. This permits occurrence of secondary compression simultaneously with primary consolidation by adding an additional term to the governing differential equation. This is different from the traditional approach, in which secondary compression begins only after primary consolidation “ends”. In addition, compressibility and permeability evolve as consolidation progresses, which differs from Terzaghi’s linear one-dimensional consolidation theory. Details can be found in a paper that is linked from the above URL.