&reftitle.constants; &extension.constants.core;

`MT_RAND_MT19937` (`int`)

- Indicates that the correct Mt19937 (Mersenne Twister) implementation will be used by the algorithm, when creating a `Random\Engine\Mt19937` instance using `Random\Engine\Mt19937::__construct` or seeding the global Mersenne Twister with `mt_srand`.

`MT_RAND_PHP` (`int`)

- Indicates that an incorrect Mersenne Twister implementation will be used by the algorithm, when creating a `Random\Engine\Mt19937` instance using `Random\Engine\Mt19937::__construct` or seeding the global Mersenne Twister with `mt_srand`.

  The incorrect implementation is available for backwards compatibility with `mt_srand` prior to PHP 7.1.0.

  &warn.deprecated.feature-8-3-0;