namespace std::chrono {
  class month_weekday_last {
    chrono::month        m_;    
    chrono::weekday_last wdl_;  
  public:
    constexpr month_weekday_last(const chrono::month& m,
                                 const chrono::weekday_last& wdl) noexcept;
    constexpr chrono::month        month()        const noexcept;
    constexpr chrono::weekday_last weekday_last() const noexcept;
    constexpr bool ok() const noexcept;
  };
}
month_weekday_last represents the last weekday of a month,
of an as yet unspecified year
.  To do this the 
month_weekday_last stores a 
month and a 
weekday_last.[
Example 1: 
constexpr auto mwd
    = February/Tuesday[last];   
static_assert(mwd.month() == February);
static_assert(mwd.weekday_last() == Tuesday[last]);
 — 
end example]
month_weekday_last is a trivially copyable and standard-layout class type
.