Add textual captions to the display. Spread out structures on screen. Superimpositions molecules or files of molecules. Often used to move, delete, recolor, etc subsets of atoms. Quite useful for defining complex set of atoms based on their properties, connectivity or distance.
Boolean operations allows generation of highly specific sets of atoms.
Residue, molecule or atom based set selections. The constants for the equations and the references from which they were obtained are read in from and external file called nmr.dat. Various coloring schemes dot surface densities are available. Surface area calculations also available.