fluid_box.base_area - I assume this means 'capacity' and defaults to 1?
fluid_box.base_level - seen on entities that produce or consume fluid, my guess is that -1 = input, 1 = output but no idea what anything between those values would be...?
flow_length_in_ticks - seen on storage tanks and a few other places, I have no idea what "flow length" means.
Any help greatly appreciated
