Tenn. Code Ann. § 47-26-905: Secondary and field standards

(a) The commissioner may acquire by purchase at least one set of copies of the primary standards to be kept in a place designated by the commissioner and to be known as secondary standards, and also such field standards and other equipment as may be found necessary to carry out this part.

(b) The secondary standards and field standards shall be verified upon their initial receipt and as often thereafter as deemed necessary by the commissioner.