wp-includes/ms-default-constants.php:101Defines Multisite file constants.
function ms_file_constants() { /** * Optional support for X-Sendfile header * * @since 3.0.0 */ if ( ! defined( 'WPMU_SENDFILE' ) ) { define( 'WPMU_SENDFILE', false ); } /** * Optional support for X-Accel-Redirect header * * @since 3.0.0 */ if ( ! defined( 'WPMU_ACCEL_REDIRECT' ) ) { define( 'WPMU_ACCEL_REDIRECT', false ); }}Introduced in 3.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/ms-default-constants.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.