I seem to remember that Rolls-Royce insisted that when the throttle valve on a Merlin engine was wide open this was zero throttle, and quite right too. Idle was at about 85 degrees because the engine couldn't start with the throttle fully closed. But when the throttle levers were pushed fully forward for take-off the boost controllers partially closed the throttles to prevent over-boosting. The degree of closure depended on the density altitude (QFE, OAT) so who could say where the throttles were? And so the power lever was born, later to become the more trendy thrust lever. HTH
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