Ok, as you and others have pointed out - the iterator of a vector doesn't have to be T: https://en.cppreference.com/w/cpp/container/vector https://en.cpprefere

Ok, as you and others have pointed out - the iterator of a vector doesn't have to be T: https://en.cppreference.com/w/cpp/container/vector https://en.cppreference.com/w/cpp/container/vector It _may_ be a T, or anything satisfying LegacyRandomAccessIterator. > just like a cat is animal does not imply an animal is a cat, It's not "just like" that. Among other differences between the pairs of concepts: The concept of an animal didn't arise as a generalization of cats.