Forget the documentation. This tinny WordPress plugin can generate all the code for you so that you don't need to roam here and there to search the code of the ACF plugin.

With support as WooCommerce serial generator for your sale and on your WooCommerce PDF Invoices You can create and generate serials and codes. Print them on your products boxes or manuals. Your customer can check if the code is valid on your website. The Premium allows you also to activate user registration and more. This allows your user to register them self to a serial number. Generate numbers and serial codes that can be validated on your site. It is a good plugin for small businesses that want an easy solution to create a large amount of numbers or serials and store them. It can for example be used to create numbers and serial codes for products and let users validate them on your site.