A doubly linked list is one where each element has pointers forwards to the next element and backwards to the previous element. The list is circular - the last element points forwards to an anchor point, and the anchor point points back to the last element.
Anchor points are always referred to as headers.
A doubly linked list is useful for maintaining a circular queue of items.
Doubly linked lists involve the creation and use of the classes:
TDblQueLink
TDblQue<class T>
TDblQueIter<class T
In practice, these classes are almost always used as components of other classes.