...
The Map and Blur parameters corresponds to the projection of images (see paragraph below). The Emission color and Intensity settings work here identical than on regular Area emitters.
The main parameters on a spot light are the Cone Angle (a), the FallOff Angel (b) and the FallOff Type(c).
...
Being a spot emitter, the emitting object will be automatically hidden to camera, so the object itself remains invisible in the render.
Setting up an image projector: Choose the image Map, adjust the Blur and the emitting intensity
...