What do the top-row engine gauges on a Boeing 707-420 measure?

Question

On Boeing 707s with Pratt and Whitney engines there are five rows of engine gauges between the Captain's and Co-Pilot's flight instruments. From top to bottom, they are Engine Pressure Ratio, N1 RPM, Exhaust Gas Temperature, N2 RPM and Fuel Flow.

The Rolls-Royce Conway powered 707-420 has gauges calibrated in percentage on the top row instead of EPR gauges. There are still five rows in total, with the N1 and N2 RPM gauges the same as in other 707s, so what are the top-row gauges measuring? Are they EPR renormalized as a percentage of maximum thrust, pressure difference (which would decrease with altitude), or something else entirely?

Answer 1

I think they're still EPR which is basically the input pressure versus the output pressure. 1/1=1 the lower the percentage the better engine output.