17 U.S. Code § 909 - Mask work notice
Mask work notice
The owner of a mask work provided protection under this chapter may affix notice to the mask work, and to masks and semiconductor chip products embodying the mask work, in such manner and location as to give reasonable notice of such protection. The Register of Copyrights shall prescribe by regulation, as examples, specific methods of affixation and positions of notice for purposes of this section, but these specifications shall not be considered exhaustive. The affixation of such notice is not a condition of protection under this chapter, but shall constitute prima facie evidence of notice of protection.
(b) The notice referred to in subsection (a) shall consist of—
the words “mask work”, the symbol *M*, or the symbol Ⓜ (the letter M in a circle); and
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