COPY word [INVERT]
The COPY command is used to copy the information stored for a previous residue into the current residue. The name of the previous residue is given by the word following the COPY verb. It can only be used at the beginning of a residue specification. The INVERT option cause the program to invert all the torsion angles specified in the BILD commands, see RTF Build Command.
The COPY command is most useful when two residues are nearly identical, and you do not wish to keep multiple copies of identical information. For example, it is used in the specification of D amino acids.