{ $<$ constraints-interaction-statement $>$ } END is invoked from the main level of X-PLOR.
INTEraction=$<$selection$>$ $<$selection$>$ [ { $<$weight-statement$>$ } ] specifies the two selected sets of atoms. The double selection is active until a new CONStraints $<$ constraints-interaction-statement $>$ statement is issued. The default double selection is a single double selection involving all atoms of the molecular structure.
VWEIghts {$<$*energy-term*$>$ $<$real$>$ } END
applies the
weight(real) to the specified energy term for computing $V_{total}$ (default : all terms having zero VWEIghts; i.e., no perturbation analysis is being done). This Hamiltonian does not contribute to the forces, but it can be used for purposes of analysis.
WEIGhts {$<$*energy-term*$>$ $<$real$>$ } END
applies the
weight (real) to the specified energy term for the Hamiltonian $E_{total}$ (default: all active terms having unit WEIGhts).

Xplor-NIH 2023-11-10