FLEX thrust can be as low as 75% of full thrust, yet it is always more than or equal to Max Cont Thrust at ISA +40? So this MCT at ISA +40 is some sort of lower limit?
I don't think so, at least for Boeing and the GE CF6...
Since the allowed assumed temperature goes as high as 65C (or thereabouts), I must assume the minimum TO thrust is full TO thrust at 65C or ISA +50. In our operations, the OPS performance computer adjusts to also ensure no more than a 25% reduction.