For the 340 you have; de-rate, flex and TOGA (Take-off Go Around) thrust.
De rate is used in very very cold conditions to produce LESS thrust so in case of an engine failure on the ground you can control the swing...so less thrust (slower acceleration) allows for a heavier take off weight. Ask the Finns and the Swedes. Pop VMCG into a search..NB your operator MUST have authority for this.
Flex thrust is thrust corrected for temp. Ie the maximum take off weight at 46 deg is 350 000KG. If we weigh 350 tons on a 25 deg c day we tell the engines to produce power as per a 46 deg c day..accelerate slower but quiet safe.
TOGA if runway is contaminated or required for performance... TOGA take -offs in lightweight big jets are reasonably exciting!
