ggofpac
A320 FCOM 2-02-10 p.1 has a graph ..
TOGA gives the manufacturer's rated thrust up to TREF (varies with altitude) e.g. ISA+31. Above TREF TOGA thrust reduces with increasing temperature up to TMAX, above which the a/c is not permitted to take off.
The graph line is "flat" (horizontal) up to TREF hence the expression "flat-rated".
Neupielot
So does it mean that if I go TOGA thrust take off, it's the SAME thrust as if i'm doing a flex 46 take off?
No. See above.