When a substance is produced, the manufacturer would assign a unique Product Code to it - just like a model number being given to a new television or a bar code to a shopping item. This product code can then be used to help identify the substance later on.

Because this code is set by the manufacturer, users cannot change them. However, users can assign their own codes to substances by adding an Internal Code. To find out how to add an internal code to a substance, please click here.