| OddParity | System.Posix.Terminal, System.Posix |
| OpenFileFlags |
| 1 (Type/Class) | System.Posix.IO, System.Posix |
| 2 (Data Constructor) | System.Posix.IO, System.Posix |
| OpenFileLimit | System.Posix.Unistd, System.Posix |
| OpenMode | System.Posix.IO, System.Posix |
| OutputQueue | System.Posix.Terminal, System.Posix |
| openDirStream | System.Posix.Directory, System.Posix |
| openFd | System.Posix.IO, System.Posix |
| otherExecuteMode | System.Posix.Files, System.Posix |
| otherModes | System.Posix.Files, System.Posix |
| otherReadMode | System.Posix.Files, System.Posix |
| otherWriteMode | System.Posix.Files, System.Posix |
| outputSpeed | System.Posix.Terminal, System.Posix |
| ownerExecuteMode | System.Posix.Files, System.Posix |
| ownerModes | System.Posix.Files, System.Posix |
| ownerReadMode | System.Posix.Files, System.Posix |
| ownerWriteMode | System.Posix.Files, System.Posix |
