Tracks What do fast_lane_with_grid.ai and pit_lane_with_grid.ai do?

[Sim_Misg]

As the title says, what do fast_lane_with_grid.ai and pit_lane_with_grid.ai do? CSP AI cache will generate a pit_lane_with_grid.ai which seems to be a copy of the existing pit_lane file. Some mods have fast_lane_with_grid.ai. When does the AI use those lines?