[O]

1. OFFSETTYPE_MAX
2. OFF_FROM_HEADER
3. OFF_T_BITWIDTH
4. OLDGNU_MAGIC
5. OPT_FLUSH
6. OPT_IGNORE_ERROR
7. OP_COPY
8. OP_DELETE
9. OP_MOVE
10. OS_SORT_CASE_SENSITIVE_DEFAULT
11. OS_Setup
12. OTHER_DIR
13. OTHER_PFX
14. O_ALL
15. O_BINARY
16. O_LINEAR
17. O_NONBLOCK
18. OperationMode