Mass. Gen. Laws ch. 143, § 3U: Labeling of safety glazing materials

Section 3U. Each light of safety glazing material manufactured, distributed, imported, or sold for use in hazardous locations or installed in such a location within the commonwealth shall be permanently labeled by such means as etching, sandblasting, firing of ceramic material on the safety glazing material, or by other suitable means so as to be easily visible and legible. The label shall identify the labeler, whether manufacturer, fabricator or installer, and the nominal thickness and the type of safety glazing material and the fact that said material meets the test requirements of section three T.

Such safety glazing labeling shall not be used on other than safety glazing materials.