woocommerce_navigation_menu_category_items filter-hook . WC 1.0

Usage

add_filter( 'woocommerce_navigation_menu_category_items', 'filter_function_name_9747' );
function filter_function_name_9747( $category_menu_items ){
	// filter...

	return $category_menu_items;
}

$category_menu_items

-

Where the hook is called

return apply_filters( 'woocommerce_navigation_menu_category_items', $category_menu_items );

Where in WP core the hook is used WooCommerce