Guideline (National Institue of Standards and Technology)*
Where possible, eliminate non-comparable methods of sale (e.g., weight and measure) for the same produce item as it can confuse consumers when more than one method of sale is used in the same outlet for the same product. This guideline applies to all sales of fruits and vegetables.
Table A lists specific commodities, Table B, general commodity groups. Items may be sold by any method of sale with an X. Check Table A first to find those commodities that either don't fit into any of the general groups or have unique methods of sale. If the item is not in Table A, check table B. (Amended 2008)
It is recommended that you treat all onions alike when applying the methods of sale in these tables. The list of examples in the table is not all inclusive. Kenneth S. Butcher, Group Leader, NIST Weights and Measures Division
Green Top Vegetables