[U]

[..]
  1. UID_CACHE_SIZE
  2. UNGET_FILE
  3. UNKNCHAR
  4. UNKNOWN
  5. UP_KEEPSEL
  6. UP_ONLY_CURRENT
  7. UP_OPTIMIZE
  8. UP_RELOAD
  9. URL_FLAGS_NONE
  10. URL_NOSLASH
  11. URL_USE_ANONYMOUS
  12. USBDEVICE_SUPER_MAGIC
  13. USE_STATVFS
  14. UTF8_CHAR_LEN
  15. UX
  16. UY
[..]