>>125
>you could imagine a header file that states that some linked list or array is to be treated as unordered by all code and anyone depending on the ordering is doing so at his own risk (because other functions that operate with it may change it in ways which are not specified in this "contract").
A linked list preserves an order of a list. Even if the items in that list are unordered. Cripes, get a freaking data structures book and look how insert() and deletion() are done on the list.