From the article:

“This is a technical document describing the UnrealScript language. It’s not a tutorial, nor does it provide detailed examples of useful UnrealScript code. For examples of UnrealScript the reader is referred to the source code of the engine, which provides tens of thousands of lines of working UnrealScript code which solves many problems such as AI, movement, inventory, and triggers. A good way to get started is by looking at the “Actor”, “Object”, “Controller”, “Pawn”, and “Weapon” scripts.”

http://udn.epicgames.com/Three/UnrealScriptReference.html