[boost] [concept_check] Should OutputIterator check for output_iterator_tag?

Hello, In tracking down a problem with Boost.MultiArray, I'd like to write a test case that exhibits the failure. Specifically, certain iterators should be models of OutputIterator, and it's my impression that an output iterator needs to have an iterator_category that's convertible to output_iterator_tag(). However, it looks like the OutputIterator Concept checker in the concept checker library does not check that the output iterator has such an iterator_category. Is that an oversight, or is it not the case that an output iterator have a category that's convertible to output_iterator_tag? It looks like InputIterator, RandomAccessIterator concept checkers perform such a check. Thanks, Ron