22 General utilities library [utilities]

22.12 Execution policies [execpol]

22.12.4 Sequenced execution policy [execpol.seq]

class execution::sequenced_policy { unspecified };
The class execution​::​sequenced_­policy is an execution policy type used as a unique type to disambiguate parallel algorithm overloading and require that a parallel algorithm's execution may not be parallelized.
During the execution of a parallel algorithm with the execution​::​sequenced_­policy policy, if the invocation of an element access function exits via an exception, terminate is invoked ([except.terminate]).