That T<20 s makes reference to inadvertently selecting the engine master OFF during flight, and then quickly reselecting ON. With these two consecutive actions, the FADEC, regardless of engine mode selector position, will try a quick relight if within the "Windmill Quick Relight" speed envelope.
You can reach this conclusion after reading "FCOM - DSC - 70 - 80 - 30 - Continuous Ignition" and the [QRH] Engine Relight procedure.