How to set initial condition for SIM/Predict/ Forecast

I'm simulating a system that has a few models work in sequences. The last output of the previous model will be the initial condition for the next one. The function 'simOptions' and 'InitialCondition - io'(below) seem to be the right one. I have tried to set the io structure many time, but still cannot get it right. Anyone can show me some samples please. I'm using both Transfer function and State Space model. Thanks

y = sim(sys,data,opt) opt = simOptions(Name,Value) 'InitialCondition' io — Structure with thefollowing fields