[U]

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