[u]

[..]
  1. u_char
  2. uid_t
  3. umode_t
  4. un_wp_page
  5. unblank_screen
  6. unexpected_floppy_interrupt
  7. unexpected_hd_interrupt
  8. unlock_buffer
  9. unlock_inode
  10. unsignify
  11. update_screen
  12. usage
  13. ushort
  14. ustat
  15. utimbuf
  16. utsname
[..]