Loc
Loc merge packets are used to merge a given loc's model with the player's own model, preventing any visual clipping problems in the process. This is commonly done with obstacle pipes in agility courses, as the player model will otherwise render through the pipes.
The merge will cover a rectangle defined by the minX, minZ, maxX and maxZ properties, relative to the player who is being merged. It should be noted that the client adds an extra 1 to the total width/height values here, so having all these properties at zero would still create a single tile square to be merged.