33 C.F.R. § 149.570
(a) Each platform, single point mooring, or submerged turret loading (STL) that protrudes above the water or is marked by a buoy must display the name of the deepwater port and the name or number identifying the structure, so that the information is visible:
(b) The information required in paragraph (a) of this section must be displayed in numbers and letters that are:
[USCG-1998-3884, 71 FR 57651, Sept. 29, 2006, as amended by USCG-2013-0397, 78 FR 39179, July 1, 2013]