SDCL § 37-20-3: Reference standards, working standards, and field standards.

In addition to the state reference standards of weights and measures provided for by law, the state shall supply at least one complete set of duplicate standards which shall be kept at all times in the department. The duplicate standards shall be known as the working standards. The other weights, measures, and apparatus which are necessary to carry out the provisions of chapters 37-20 to 37-22, inclusive, shall be known as field standards.