19 General utilities library [utilities]

19.18 Execution policies [execpol]

19.18.6 Parallel and unsequenced execution policy [execpol.parunseq]

class execution::parallel_­unsequenced_­policy { unspecified };
The class execution::parallel_­unsequenced_­policy is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and indicate that a parallel algorithm's execution may be parallelized and vectorized.
During the execution of a parallel algorithm with the execution::parallel_­unsequenced_­policy policy, if the invocation of an element access function exits via an uncaught exception, terminate() shall be called.