Iterator Categories

The Output Iterator (output_iterator_tag) category is the only iterator category not related to the other iterator categories by inheritance:

• Input Iterator (input_iterator_tag)
  
• Forward Iterator (forward_iterator_tag)
  
• Bidirectional Iterator (bidirectional_iterator_tag)
  
• Random Access Iterator (random_access_iterator_tag)
  

Reference: The C++ Standard Library: A Tutorial and Reference by Nicolai M. Josuttis. Addison-Wesley, 1999, p. 284.