XCCR {<CCR-statement>} END
    ASSIgn <sel> <sel> <sel> <real> <real>
           ! Restraint: Metal, coupled nucleus, detected 
           ! nucleus, CCR, err.
    CLASsification <name>
           ! Starts a new class.
    WEIP <1 | 0>
           ! Switch weighting from uniform (0) to proportional 
           ! to R^3 (1)
    COEFficient <real>
           ! Proportionality constant.
    FORCeconstant <real>
           ! Force constant for the current class.
    NREStraints <integer>
           ! Number of slots for restraints.
    PRINt THREshold <real>
           ! Prints violations larger than the specified value.
           ! Erases the restraint table.
    FRUN <integer>
           ! Runs FANTACROSS for fitting the proportionality 
           ! constant. This is done for each class. Classes 
           ! are labeled by number, not name.

Xplor-NIH 2023-11-10