Section 172.304 - Marking requirements(a) The marking required in this subpart-(1) Must be durable, in English and printed on or affixed to the surface of a package or on a label, tag, or sign.(2) Must be displayed on a background of sharply contrasting color;(3) Must be unobscured by labels or attachments; and(4) Must be located away from any other marking (such as advertising) that could substantially reduce its effectiveness.Amdt. 172-29, 41 FR 15996, 4/15/1976, as amended by Amdt. 172-29B, 41 FR 57067, 12/30/1976