[U]

1. UCHAR_MAX
2. UESP
3. UINT_MAX
4. ULONG_MAX
5. ULTRASTOR_14F
6. UNBLK_FIRST
7. UNBLK_SECOND
8. UNIT_ATTENTION
9. UN_BUF_AVAIL
10. UN_BUF_SPACE
11. UN_DATA
12. UN_PATH_OFFSET
13. US14F_PRODUCT_ID_0
14. US14F_PRODUCT_ID_1
15. USED
16. USHRT_MAX
17. UTS_MACHINE
18. UTS_NODENAME
19. UTS_RELEASE
20. UTS_SYSNAME
21. UTS_VERSION