+Routines to manipulate queues built from doubly linked lists. The
+@code{insque} routine inserts @var{elem} in the queue immediately
+after @var{pred}. The @code{remque} routine removes @var{elem} from
+its containing queue. These routines expect to be passed pointers to
+structures which have as their first members a forward pointer and a
+back pointer, like this prototype (although no prototype is provided):