Digestroids

I have been pouring over the code for the provided sample "Digestroids" What does extending TLINK or TLIST do for you? I'm getting alittle confused on the implementation.

Type TPhysicsProviderCollection Extends TList

 	Method Draw()
		Local Item:TPhysicsProvider
		For Item=EachIn Self
			Item.Draw()
		Next
        End Method
End Type

Thanks,
Eric

this is a guess but I would say in this situation he just wanted to be able to call Draw() on the list to draw everything without having to have the loop in his game loop.