The need to balance the practical requirements determining the number of grades adds to the problems of devising a satisfactory system. Of course, consumers need not be informed on the technical aspects of grades so long as the storekeeper selects by those grades and provides the shopper with consistency. Because grades balance a number of disparate factors, they are inherently judgemental. The Food Production Act of 1917 encouraged the development and use of grades as part of the effort to supply Unied States and allied troops during the war. Carcass grading is done in the packing plant by USDA Food Safety and Inspection Service employees, and the grade is stamped on the carcass with the same color ink as the inspection stamp. The value of grading can be conceptualized by considering a shopper attempting to locate a package of lean bacon in a supermarket. Grading, by saving time for consumers, can then make the market more efficient.