wp-includes/option.php:2743Registers default settings available in WordPress.
function register_initial_settings() { register_setting( 'general', 'blogname', array( 'show_in_rest' => array( 'name' => 'title', ), 'type' => 'string', 'label' => __( 'Title' ), 'description' => __( 'Site title.' ), ) ); register_setting( 'general', 'blogdescription', array( 'show_in_rest' => array( 'name' => 'description', ), 'type' => 'string', 'label' => __( 'Tagline' ), 'description' => __( 'Site tagline.' ), ) ); if ( ! is_multisite() ) { register_setting( 'general', 'siteurl', array( 'show_in_rest' => array( 'name' => 'url', 'schema' => array( 'format' => 'uri', ), ), 'type' => 'string', 'description' => __( 'Site URL.' ), ) ); } if ( ! is_multisite() ) { register_setting( 'general', 'admin_email', array( 'show_in_rest' => array( 'name' => 'email', 'schema' => array( 'format' => 'email', ), ), 'type' => 'string', 'description' => __( 'This address is used for admin purposes, like new user notification.' ), ) ); } register_setting( 'general', 'timezone_string', array( 'show_in_rest' => array( 'name' => 'timezone', ), 'type' => 'string', 'description' => __( 'A city in the same timezone as you.' ), ) ); register_setting( 'general', 'date_format', array( 'show_in_rest' => true, 'type' => 'string', 'description' => __( 'A date format for all date strings.' ),Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/option.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.