| Allowed Value | Details | 
|---|---|
| D | distance or angle restraint on positional coordinates | 
| DG | combination of the above constraints | 
| DGR | combination of the above constraints | 
| DGRS | combination of the above constraints | 
| DGS | combination of the above constraints | 
| DR | combination of the above constraints | 
| DRS | combination of the above constraints | 
| DS | combination of the above constraints | 
| G | rigid-group refinement of positional coordinates | 
| GR | combination of the above constraints | 
| GRS | combination of the above constraints | 
| GS | combination of the above constraints | 
| R | riding-atom site attached to non-riding atom | 
| RS | combination of the above constraints | 
| S | special-position constraint on positional coordinates | 
| Allowed Value | Details | 
|---|---|
| D | distance or angle restraint on positional coordinates | 
| DG | combination of the above constraints | 
| DGR | combination of the above constraints | 
| DGRS | combination of the above constraints | 
| DGS | combination of the above constraints | 
| DR | combination of the above constraints | 
| DRS | combination of the above constraints | 
| DS | combination of the above constraints | 
| G | rigid-group refinement of positional coordinates | 
| GR | combination of the above constraints | 
| GRS | combination of the above constraints | 
| GS | combination of the above constraints | 
| R | riding-atom site attached to non-riding atom | 
| RS | combination of the above constraints | 
| S | special-position constraint on positional coordinates |