[ Summit: ]

We agree that this section needs concepts. We look forward to a paper on this topic. We recommend no action until a paper is available.

Addresses JP 45 [CD1]

Rep, Period, Clock and Duration don't correspond to concept.

template <class Rep, class Period = ratio<1>> class duration; 
template <class Clock, class Duration = typename Clock::duration> class time_point; 

Make concept for Rep, Period, Clock and Duration. Fix [time] and wait_until and wait_for's template parameter at [thread].