§ 90.1 Purpose
This part contains the interpretative rules for the Inland Rules. These interpretative rules are intended as a guide to assist the public and promote compliance with the Inland Rules.

§ 90.3 Pushing vessel and vessel being pushed: Composite unit 
Rule 24(b) of the Inland Rules states that when a pushing vessel and a vessel being pushed ahead are rigidly connected in a composite unit, they are regarded as a power-driven vessel and must exhibit the lights prescribed in Rule 23. A "composite unit" is interpreted to be the combination of a pushing vessel and a vessel being pushed ahead that are rigidly connected by mechanical means so they react to sea and swell as one vessel. Mechanical means does not include lines, wires, hawsers, or chains.

§ 90.5 Lights for moored vessels
A vessel at anchor includes a vessel made fast to one or more mooring buoys or other similar device attached to the ocean floor. Such vessels may be lighted as a vessel at anchor in accordance with Rule 30, or may be lighted on the corners in accordance with 33 CFR 88.13.

§ 90.7 Sidelights for unmanned barges
An unmanned barge being towed may use the exception of COLREG Rule 24(h). However, this exception only applies to the vertical sector requirements.