Pondering removing these identifiers from <iso/ctype_iso.h> in my build sandboxes:
#define _U 0x00000001
#define _L 0x00000002
#define _N 0x00000004
#define _S 0x00000008
#define _P 0x00000010
#define _C 0x00000020
#define _B 0x00000040
#define _X 0x00000080
Software authors don't respect namespace rules, and I have to patch around them every so often.
If anyone wants a trivial but tedious #illumos bug to work on, rename them to _CTYPE_* like the BSDs.