std::experimental::parallel::seq, std::experimental::parallel::par, std::experimental::parallel::par_vec

Defined in header `<experimental/execution_policy>`
constexpr sequential_execution_policy seq{};
constexpr parallel_execution_policy par{};
constexpr parallel_vector_execution_policy par_vec{};

seq, par and par_vec are instances of the execution policy types sequential_execution_policy, parallel_execution_policy and parallel_vector_execution_policy respectively. They are used to specify the execution policy of parallel algorithms - i.e., the kinds of parallelism allowed.

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Technical Specifications

Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
Extensions for parallelism (parallelism TS)
Concepts (concepts TS)
Extensions for concurrency (concurrency TS)

Execution policies
parallel::execution_policy
parallel::sequential_execution_policyparallel::parallel_execution_policyparallel::parallel_vector_execution_policy
parallel::seqparallel::parparallel::par_vec
Parallel algorithms
Parallel exceptions
parallel::exception_list
Parallelized version of existing algorithms
New algorithms
parallel::for_eachparallel::for_each_n
parallel::reduce
parallel::exclusive_scan
parallel::inclusive_scan
parallel::transform_reduce
parallel::transform_exclusive_scan
parallel::transform_inclusive_scan