The class template array synopsis in [array] p. 3 declares a member function

void assign(const T& u);

which's semantic is no-where described. Since this signature is not part of the container requirements, such a semantic cannot be derived by those.

I found only one reference to this function in the issue list, 588 where the question is raised:

what's the effect of calling assign(T&) on a zero-sized array?

which does not answer the basic question of this issue.

If this function shall be part of the std::array, it's probable semantic should correspond to that of boost::array, but of course such wording must be added.