cpp/algorithm/execution policy tag

The execution policy types
 * std,
 * std,
 * std, and
 * std

have the following respective instances:


 * , and
 * , and
 * , and

These instances are used to specify the execution policy of parallel algorithms, i.e., the kinds of parallelism allowed.

Additional execution policies may be provided by a standard library implementation (possible future additions may include and ).