My post about Gym Day brought laughter to many people 😆
https://www.gn-app.com/posts/6ead9236-2c12-4027-b883-03df63f7fee6
The term "reef sector" wasn't used in the original series, but it appears as a setting in later works, such as the Garden of Thorns and the Thunderbolt Sector.
Reef sectors are filled with various types of space debris, including large colony and battleship wreckage, making them convenient locations for secret experiments and the hiding places of various factions.
The Corregidor Reef Sector is located midway between Solomon and A Baoaqua.

Corregidor Reef Sector | nobu(BN界の鳥肌実)'s Gunpla works