Lock.
(13) Lock. A device that utilizes a positive means, either a key or combination lock, to hold an energy-isolating device in a safe position that prevents the release of energy and the startup or energization of the machinery, equipment, or system to be serviced.
Source
29 CFR § 1915.80
Scoping language
The provisions of this subpart apply to general working conditions in shipyard employment, including work on vessels, on vessel sections, and at landside operations, regardless of geographic location.