Thrust bump. It's a modified FADEC software which will give an extra 'couple of percent' available thrust for the hot and/or high airfield. It uses IIRC a different assumed temperature. Entered via the CDU the FADEC takes care of the rest. It shortens the engine life and costs a lot of dosh if you're on power by the hour.
Only available whilst the engine has a reasonable EGT margin.
I think that about sums it up!