wp-admin/includes/class-wp-ms-sites-list-table.php:545Handles the registered column output.
$blogarray public function column_registered( $blog ) { global $mode; if ( 'list' === $mode ) { $date = __( 'Y/m/d' ); } else { $date = __( 'Y/m/d g:i:s a' ); } if ( '0000-00-00 00:00:00' === $blog['registered'] ) { echo '—'; } else { echo mysql2date( $date, $blog['registered'] ); } }Introduced in 4.3.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-ms-sites-list-table.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.