Final answer:
The question deals with the IALA B Lateral Mark Port Hand in maritime navigation, which indicates that vessels should keep it on their port side, identified by its unique light pattern, green cylindrical top mark, and region-specific letters and odd numbers.
Step-by-step explanation:
The question refers to the IALA B Lateral Mark Port Hand used in maritime navigation under the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) system B. These marks indicate that vessels should keep the mark on their port (left) side when proceeding in the conventional direction of buoyage (towards the source of rising tide or from open sea into port). The lights mentioned describe the flashing characteristics of the buoy or marker, in this case, Flashing Green (Fl G) with one flash every 4 seconds. Top Marks consist of a green cylinder, assisting mariners in identifying the mark during the daytime. Identification is further simplified through the use of letters and odd numbers, with the letter often indicating the region of the mark and the odd number signifying its position within a channel or route.