Hy Port Strobe.
There are 2 types of engine rating:Full rated and flat rated.
Normally your engine thrust is limited by the OAT. Theoretically you have more thrust at low OAT till you reach the EGT limit.
OTOH your thrust decrease linear by rising OAT.
Full rated engines normally are used by military. But the wear of the engine is extreme (who cares: government pays!?
)
Airlines normally use flat rated engines. That means you donīt use the max. possible thrust at low OAT.
The manufacturer define a OAT on whitch you have the maximal thrust regardless how low the OAT is.
The trust only decrease if OAT goes over the manufacturer define a OAT.
If you make a drawing of thrust versus OAT, you get a "flat" line at low OATs and voila "Flat rated"
But pictures says more than explanation in my non native language:
HIH
Ingo