Iowa Code § 215.18: Specifications and tolerances.

The specifications, tolerances, and other technical requirements for commercial, law enforcement, data gathering, and other weighing and measuring devices, as adopted by the national conference on weights and measures and published in the national institute of standards and technology, handbook 44, “Specifications, tolerances, and other technical requirements for weighing and measuring devices”, shall apply to weighing and measuring devices in this state, except insofar as modified or rejected by rule and shall be observed in all inspections and tests.