Supply Line is a game mode intended for Battlefield 2 but was eventually cut. Its mechanism is unknown, but in \python\bf2\stats\constants.py it is listed as gpm_sl as the second game mode alongside with Conquest. Furthermore, in \mods\bf2\Menu_client.zip\HUD\Texture\Ingame\Flags\Icons\Minimap\, in addition to the folders containing flag icons for the minimap to mark locations of control points, there is another folder named SupplyLine containing six images.