| OAbs | Control.CP.FD.OvertonFD.OvertonFD |
| OAdd | Control.CP.FD.OvertonFD.OvertonFD |
| OConstraint | Control.CP.FD.OvertonFD.OvertonFD |
| ODiff | Control.CP.FD.OvertonFD.OvertonFD |
| OHasValue | Control.CP.FD.OvertonFD.OvertonFD |
| old | Control.Search.GeneratorInfo |
| OLess | Control.CP.FD.OvertonFD.OvertonFD |
| OLessEq | Control.CP.FD.OvertonFD.OvertonFD |
| OMult | Control.CP.FD.OvertonFD.OvertonFD |
| onAbort | Control.Search.GeneratorInfo |
| once | Control.Search.Combinator.Once |
| onceOld | Control.Search.Combinator.Once |
| onCommit | Control.Search.GeneratorInfo |
| onCommit' | Control.Search.GeneratorInfo |
| OptimDirection | Control.CP.FD.SearchSpec.Data |
| Or | Control.Search.Language |
| orRepeat | Control.Search.Combinator.OrRepeat |
| OSame | Control.CP.FD.OvertonFD.OvertonFD |
| OSub | Control.CP.FD.OvertonFD.OvertonFD |
| OutS | Control.Search.Generator |
| OvertonFD | Control.CP.FD.OvertonFD.OvertonFD |