Larry, I think Energy x Current probably belongs in another dimension! "Set phasers to exterminate!"
Electric power = current times the potential difference;
Unit of power: watt = (amperes x volts)
P = IxV : Power = current x voltage.
P = IxI x R ; Power [loss] = current squared x circuit resistance.
Peering into my Dilithium Crystal Ball, could this meter have been used in an electric traction operation? Measuring Amps squared x hrs on a known resistance of track/overhead wires [got from the voltage drop] could indicate the non-traction losses with no traffic = leakage/signalling etc., over a timebase. Compared to circuit losses with traffic, giving an efficiency factor. The actual resistance of the track would be treated as a constant. Could the same meter be used on other power transmission circuits, within voltage limits, for power loss assessment? That might explain why it only has a simple additive totals scale.