PART 90—INLAND RULES: INTERPRETATIVE RULES Authority: 33 U.S.C. 2071; 49 CFR 1.46(n)(14). Source: CGD 83-011, 48 FR 51622, Nov. 10, 1983, unless otherwise noted. § 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 push 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 [CGD 94-011, 63 FR 5732, Feb. 4, 1998, as amended by USCG-2015-0433, 80 FR 44281, July 27, 2015] § 90.7 Sidelights for unmanned barges. An unmanned barge being towed may use the exception of COLREGS Rule 24(h). However, this exception only applies to the vertical sector requirements for sidelights. [CGD 94-011, 63 FR 5732, Feb. 4, 1998]