The Programmer
The live layer you work in.
The programmer is where you work. Every value you set in the Functions panel and every effect you start goes into it. It is a live layer that sits on top of your scenes and the timeline.
It sits above the scenes
Because the programmer sits above the scenes, its values win. You can grab any fixture and take manual control at any moment, even while a scene runs.
It can also be the reason that a scene you just stored doesn't seem to play. Your live values are still sitting on top of it. Clear the programmer and the scene appears.
Presets
A capability or value preset does not copy its values into the programmer. It puts a reference there, which is resolved live. That is why editing a preset changes what is currently on stage, and why storing a step stores the reference instead of the resolved values.
References render below your manual values, so a value you set by hand always wins over a preset on the same channel. See Presets.
Storing
Storing a step captures whatever the programmer currently holds, values, effects and preset references.
Clearing the programmer
Clear programmer empties the programmer on the first click by default, and then clears the fixture selection. This can be changed in the Settings.
Sneak out fades the programmer's dimmer and color values down to what the layers below would render and clears it afterwards, presets included. Use it during a show to get rid of a look without a sudden jump.
Disable selected in the Tricks window releases only the selected fixtures and leaves the rest of the programmer alone.
Blind Edit
Blind Edit keeps the programmer and the timeline preview out of the output. You can prepare a look, or fix a scene, without any of it being rendered.
Prepare Mode
Prepare Mode takes a different route. Instead of muting the programmer it parks it, keeps it rendering, and hands you a second, empty programmer that is not rendered. Execute merges your prepared values into the parked one and puts it back in front, Clear throws them away.
Blind Edit is the tool for fixing something without it showing. Prepare Mode is the tool for building the next look while the current one is still on stage. See Use Prepare Mode.