Jaguar PTR
My recollection is that PTR was a device to bridge the thrust gap, when on one engine, between max dry thrust, not enough, and min reheat, too much, in some configurations and weights. The reheat was thus able to light when the engine was at or above about 80%. I had an Omani student who was the first thru Lossie Ground School and he had had some 2 seater trips while were working up an Jag Aeros team (Pause for laughter and no it never did happen). However, we used PTR and a bit of flap and a good time was had by all. When this worthy was asked, in engine groundschool, what the PTR was for he replied that it was for formation aeros which produced reactions between deep shock and hysterical laughter! An excellent man, being groomed for high rank and killed himself flying a Defender up in Mussandam - a great loss.