I'm a doctor, not a mechanic
This is the specification for the Light class. For a general overview of how to light a map, see Lighting.
The Light class doesn't add any properties or script, it's in effect just a holding class with the properties required to emit light preset and an icon to display in the editor.
All actors have the light-casting properties, under the Lighting and LightColor sections (see Actor (UT)/Lighting for a full list), and thus any actor can be made to cast a light in a map. What follows is a summary of other properties relevant to casting light.
- Advanced -> bDirectional
- Spotlights set this automatically, but if you make a normal light into a spotlight by setting LightType (check), you'll need to set this manually. An actor with this set to true displays an arrow when selected and allows you to set the actor's rotation in UnrealEd. It's only a variable for the editor.
- Display -> DrawScale
- Sets the size of the icon in the editor and of coronas in the game. It's useful to set this to a larger number for lights whose icons you want to see when zoomed out in orthogonal view. Unfortunately, it makes coronas have teeny tiny icons in the editor, which is a pain.
- Display -> Skin
- The texture used for the corona and TexturePaletteOnce/Loop effect.
I imagine a lot of these don't warrant a page to themselves
- QueenTeleportLight (Freddie Mercury has left the building, perhaps?)
- TriggerLight appears in both Engine and one in UnrealShare classes
- TriggerLightRad (No code, no changes to default properties.)
Sobiwan: The class is light, not lighting. This page is partially duplicated at Actor (UT)/Lighting, whose info should probably be merged here to make it consistent.
Tarquin: No, because those are properties of the Actor class. This page is a convenience to the mapper.