EPRs are specific to individual crop varieties. A single variety can be represented in Grain Trader in several commodities (eg by grade), and a single commodity can be associated with a number of varieties. Grain Trader therefore has a mechanism to link varieties to commodities in a many-to-many relationship. This is performed using the Varieties window as shown below:

This window can be displayed either from the View menu:

or by clicking the ellipsis button on the Varieties panel of the Commodity window: