To compare the results from two dynamical calculations, one must perform the following steps: First, one must invoke a COMPARE command, see Comparisons, to establish the comparison PSF and other comparison data structures and to construct the matching of atoms between the two PSF's. If the PSF is not changed, then any averaging data structures will be assigned from the main calculation to the comparison calculation. Then, any additional comparison averaging data structures must either read in or constructed for both main and comparison. The COMPARE option in the READ, ACCUM, and COMBINE command can be used to direct the averaging data structures to the comparison data structure collection. Finally, the BUILD command using the DIFF option, see Building Tables, can be used to build tables which are the differences between the main and comparison dynamical averages.