std::experimental::parallel::sequential_execution_policy, std::experimental::parallel::parallel_execution_policy, std::experimental::parallel::parallel_vector_execution_policy
From cppreference.com
                    
                                        
                    < cpp | experimental
                    
                                                            
                    | Defined in header  <experimental/execution_policy> | ||
| class sequential_execution_policy { /* unspecified */ }; | (parallelism TS) | |
| class parallel_execution_policy { /* unspecified */ }; | (parallelism TS) | |
| class parallel_vector_execution_policy { /* unspecified */ }; | (parallelism TS) | |
sequential_execution_policy, parallel_execution_policy and parallel_vector_execution_policy are tag types used to indicate the kinds of
parallelism allowed in the execution of a parallel algorithm.


