Macros starting with `f' in sys

• FD_CLR sys/types.h:134
• FD_COPY sys/types.h:136
• FD_ISSET sys/types.h:135
• FD_SET sys/types.h:133
• FD_ZERO sys/types.h:137
• FFLAGS sys/fcntl.h:96
• FREE sys/malloc.h:262