70 Pa. Code § 23.15a
A separate statement of the net quantity of contents in terms of the metric system is not regarded as a supplemental statement, and a statement of quantity in terms of the metric system of weight or measure may also appear on the principal display panel or other panels.
The provisions of this § 23.15a adopted March 11, 1977, effective March 12, 1977, 7 Pa.B. 706.