It is mostly abstracted, but:
For planes 1 point of supply is used for every 1000 lb of bombload, so it would mean half US tonne. But including AVGAS for operation (and 1/3rd of point used for CAP mission), it gives around 1 US tonne (transport planes takes 1 point of supply per 2000 load). Point of resources, supply, and point of device weight takes 1 point of load.
FUEL is probably also measured as 1 tonne, not liquid volume, as 1 point of oil takes the same space as 1 point of fuel, and it is converted for IIRC 4 points of cargo space (4 tonnes), if transported in barrels. Also ships take it in listed amount of bunkerage.