I add a device in the IDE and the type is a “Simulated Dimmable Bulb”
“Virtual” is nomenclature from this post - FAQ: Creating a virtual Device
“…not completely” means that some of the other devices that are mirrored do not turn off, do not turn off at the some time, turn off and then turn back on again, or cause a race condition where things flicker at a slow-but-aggravating rate.