[o]

1. off_t
2. offsetof
3. old_stat
4. old_utsname
5. oom
6. open
7. open_aux
8. open_mouse
9. open_namei
10. options
11. origin
12. out_port_type
13. outb
14. outb_p
15. output_byte
16. outsw
17. outw
18. overlap