It is quite useful to analyze the packing between symmetry-related molecules in the unit cell. While some graphics programs provide a packing-analysis facility, you may find it useful to generate explicitly the symmetry-related molecules within X-PLOR. The following example generates all symmetry mates within the unit cell of the 26-10 Fab example. Note that this example generates positions for backbone atoms only. It would be easy to switch to a different selection of atoms by modifying the delete statement.