question about queue.h

[walter harms]

hi list,
i have a question about sys/queue.h (not a bug report).

sys/queue.h provides macros for links lists. the code structure looks like this:

#define LIST_ENTRY(type)
struct {                                                                \
        struct type *le_next;   /* next element */                      \
        struct type **le_prev;  /* address of previous next element */  \
}

is there any (technical) reason why (struct type **) ?

the author (?) provides also a second type that look like this:
#define CIRCLEQ_ENTRY(type)                                             \
struct {                                                                \
        struct type *cqe_next;          /* next element */              \
        struct type *cqe_prev;          /* previous element */          \
}

is the first an ancient typo that could be fixed ?

i googled a bit and found no good answer.

re,
 wh