Because of the mixing of iterator traversal and dereference return type, many useful iterators can not be appropriately categorized. For example, vector<bool>::iterator is almost a random access iterator, but -the return type is not bool& (see issue +the return type is not bool& (see issue 96 and Herb Sutter's paper J16/99-0008 = WG21 N1185). Therefore, the iterators only meet the requirements of input iterator and output iterator. This is so nonintuitive that at least one implementation erroneously assigns @@ -74,7 +74,7 @@ integers when incremented and dereferenced (see Issue +value_type. Option 1) runs into the problems discussed in Issue 198, the reference will not be valid after the iterator is destroyed. Option 2) is therefore a better choice, but then we have a counting iterator that cannot be a random access iterator.