Not sure: : should forward_iterator_tag not also inherit from truct output_iterator_tag ?

[F-Haferkorn]

Hello at all,
reading https://en.cppreference.com/w/cpp/iterator/iterator_tags,
i wonder, the inheritance structure of should forward_iterator_tag is correct herein.

Is the forward_iterator_tag not also inherit from sruct output_iterator_tag ?

it says
struct forward_iterator_tag : public input_iterator_tag {}; // (4)

Were do I find a decise manual howto properly write my own iterators for my own classes.
Yours,
Frank.Haferkorn

[PeterFeicht]

Not every forward iterator is writable, so no it should not.