get_parameter_data()

Is there a set_parameter_data?

I know that with get_parameter_data() you can get  Review Time (0=Off, 2000-10000=2-10sec, -1=Hold).

But I am looking for a way to set the camera (a590is) to 0=Off from a lua script and then have the script set camera back to -1=Hold.

Is there a set_parameter_data?

No, although the corresponding Canon function is available in C code.

These settings are stored in camera flash, so mistakes with the set_ function could have permanent consequences.

Is there any way to switch the cam to 0=Off from lua?

Is there any way to switch the cam to 0=Off from lua?

As far as I know, the only way to do this would be using key presses to navigate the canon menu. If your camera is like the ones I have, the menu always comes up in the same state (it doesn't remember which page / item you had selected) so it should be possible.