Onkyo TX-SR500 Discreet on?

So I just received my Philips Pronto and am attempting to program it. I've been attempting to locate discreet codes for my devices. So far I have an Onkyo TX-SR500 Receiver which is stumping me. I have found several sources which claim to be discreet on and off commands for this unit, and the discreet off command works perfectly, only shutting the unit off. However, the discreet on command just seems to toggle the power. Does anyone know if there is a discreet on command for this unit - I would find it odd if there was not because there is a discreet off.