What is the different between ::Rails::Engine and Rails::Engine

Question

Possible Duplicate:
Ruby’s double colon (::) operator usage differences

I've made a font-awesome plugin for Rails, in lib/rails-font-awesome.rb

module Rails
  module Font
    module Awesome
      class Engine < ::Rails::Engine
      end
    end
  end
end

Can I use Rails::Engine instead?

Answer 1

:: before Rails tells this to skip the normal traversing up the hierarchy to find the class and just go straight to the top.