wp-includes/post.php:2278Adds submenus for post types.
function _add_post_type_submenus() { foreach ( get_post_types( array( 'show_ui' => true ) ) as $ptype ) { $ptype_obj = get_post_type_object( $ptype ); // Sub-menus only. if ( ! $ptype_obj->show_in_menu || true === $ptype_obj->show_in_menu ) { continue; } add_submenu_page( $ptype_obj->show_in_menu, $ptype_obj->labels->name, $ptype_obj->labels->all_items, $ptype_obj->cap->edit_posts, "edit.php?post_type=$ptype" ); }}Introduced in 3.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/post.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.