Auto generation of product codes can be achieved when admin is turned on and the auto generate product code setting is enabled; when the setting is off the user will need to enter the code themselves. 

 

The auto generation of codes can be found in product requests; whenever approval process is on and whenever a product is added; whenever approval process is off. When the product code is auto generated it can be read only when creating the product request and it is editable when editing the product.