#define F_IS_HLINKED(f) ((f)->flags & FLAG_HLINKED)
#define F_HLINK_NOT_FIRST(f) BITS_SETnUNSET((f)->flags, FLAG_HLINKED, FLAG_HLINK_FIRST)
#define F_HLINK_NOT_LAST(f) BITS_SETnUNSET((f)->flags, FLAG_HLINKED, FLAG_HLINK_LAST)
#define F_IS_HLINKED(f) ((f)->flags & FLAG_HLINKED)
#define F_HLINK_NOT_FIRST(f) BITS_SETnUNSET((f)->flags, FLAG_HLINKED, FLAG_HLINK_FIRST)
#define F_HLINK_NOT_LAST(f) BITS_SETnUNSET((f)->flags, FLAG_HLINKED, FLAG_HLINK_LAST)