    template <
        class Iterator
      , class Value = use_default
      , class CategoryOrTraversal = use_default
      , class Reference = use_default
      , class Difference = use_default
    >
    class indirect_iterator
    {
     public:
        typedef /* see below */ value_type;
        typedef /* see below */ reference;
        typedef /* see below */ pointer;
        typedef /* see below */ difference_type;
        typedef /* see below */ iterator_category;

        indirect_iterator();
        indirect_iterator(Iterator x);

        template <
            class Iterator2, class Value2, class Category2
          , class Reference2, class Difference2
        >
        indirect_iterator(
            indirect_iterator<
                 Iterator2, Value2, Category2, Reference2, Difference2
            > const& y
          , typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
        );
    };

The member types of `indirect_iterator` are defined according to the following pseudo-code. We use the abbreviation `V=iterator_traits<Iterator>::value_type` and `v` is an object of type `V`.:

    if (Value is use_default) then
        typedef iterator_traits<V>::value_type value_type;
    else
        typedef remove_const<Value>::type value_type;

    if (Reference is use_default) then
        typedef iterator_traits<V>::reference reference;
    else
        typedef Reference reference;

    typedef Value* pointer;

    if (Difference is use_default)
        typedef iterator_traits<Iterator>::difference_type difference_type;
    else
        typedef Difference difference_type;

The member `indirect_iterator::iterator_category` is a type that satisfies the requirements of the concepts modeled by the indirect iterator as specified in the models section.

# `indirect_iterator` requirements

The `Iterator` argument shall meet the requirements of Readable Iterator. The `CategoryOrTraversal` argument shall be one of the standard iterator tags or `use_default`. If `CategoryOrTraversal` is an iterator tag, the template parameter `Iterator` argument shall meet the traversal requirements corresponding to the iterator tag.

The expression `*v`, where `v` is an object of type `iterator_traits<Iterator>::value_type`, must be a valid expression and must be convertible to `indirect_iterator::reference`. Also, there are further requirements on the `iterator_traits<Iterator>::value_type` if the `Value` parameter is not `use_default`, as implied by the algorithm for deducing the default for the `value_type` member.

# `indirect_iterator` models

If `CategoryOrTraversal` is a standard iterator tag, `indirect_iterator` is a model of the iterator concept corresponding to the tag, otherwise `indirect_iterator` satisfies the requirements of the most refined standard traversal concept that is satisfied by the `Iterator` argument.

`indirect_iterator` models Readable Iterator. If `indirect_iterator::reference(*v) = t` is a valid expression (where `t` is an object of type `indirect_iterator::value_type`) then `indirect_iterator` models Writable Iterator. If `indirect_iterator::reference` is a reference then `indirect_iterator` models Lvalue Iterator.

# `indirect_iterator` operations

`indirect_iterator();`

Requires: | `Iterator` must be Default Constructible.
Returns: | An instance of `indirect_iterator` with a default-constructed `iterator_adaptor` subobject.

`indirect_iterator(Iterator x);`

Returns: | An instance of `indirect_iterator` with the `iterator_adaptor` subobject copy constructed from `x`.

    template <
        class Iterator2, class Value2, unsigned Access, class Traversal
      , class Reference2, class Difference2
    >
    indirect_iterator(
        indirect_iterator<
             Iterator2, Value2, Access, Traversal, Reference2, Difference2
        > const& y
      , typename enable_if_convertible<Iterator2, Iterator>::type* = 0 // exposition
    );

Requires: | `Iterator2` is implicitly convertible to `Iterator`.
Returns: | An instance of `indirect_iterator` whose `iterator_adaptor` subobject is constructed from `y.base()`.