I think the explanation by HPSOV makes more sense.
If what sprucegoose and VnV2178B are saying is correct, why would one be using less than 100% for TOGA, when not using a Derate or Assumed Temp Reduced Thrust?
The B737-700 uses 88.3% Maximum TakeOff N1 for a full power Takeoff (same for Max N1% for Go-Around). If its rated power is at 100% N1, what's the whole point? The B737-700 barely reaches 100% N1, even in Max. CLIMB Power at high altitudes.