Two of my device do not have an integration, so I have learned all their IR codes.
Both remotes do not have a Power On and Power Off button, but only a Power toggle.
So depending on the previous state pressing the button results in switching state.
In the Remote 3 the State = Unknown and the Toggle button cannot switch the State.
How can I program the Remote 3 to tell that the current State = On, so that pressing the Power button switch the State from On to Off?
You cannot. But if you want to use it in activities it helps if you use your toggle also for power on and off and use these in the start/end sequence.
Ralf
Ralf, that is what I am doing, but it does not change the State, this stays unkown.
I would like to set the initial State to for example OFF.
So that when I use Power the first time in an activity the State switches to ON.
Copy your power toggle IR code. Create new IR commands called POWER_ON and POWER_OFF. Paste your power toggle IR code as the code for those commands. Use the POWER_ON and POWER_OFF commands in your On and Off Sequences
Thank you fbutler, your solution works!
Sure does work. Discovered that myself. 
This is great, thanks a lot.