std::chrono::year_month_weekday::year, std::chrono::year_month_weekday::month, std::chrono::year_month_weekday::weekday, std::chrono::year_month_weekday::index, std::chrono::year_month_weekday::weekday_indexed
From cppreference.com
                    
                                        
                    < cpplrm; | chronolrm; | year month weekday
                    
                                                            
                    | constexpr std::chrono::year year() const noexcept; | (1) | (since C++20) | 
| constexpr std::chrono::month month() const noexcept; | (2) | (since C++20) | 
| constexpr std::chrono::weekday weekday() const noexcept; | (3) | (since C++20) | 
| constexpr unsigned index() const noexcept; | (4) | (since C++20) | 
| constexpr std::chrono::weekday_indexed weekday_indexed() const noexcept; | (5) | (since C++20) | 
Retrieves the field values stored in this year_month_weekday object.
Return values
1) Returns the stored std::chrono::year value.
2) Returns the stored std::chrono::month value.
3) Returns the stored std::chrono::weekday value.
4) Returns the stored weekday index.
5) weekday()[index()].