Four views of a cyclic tag system with rules as shown above, drawn so as to be progressively closer to what can be emulated directly in rule 110. Picture (a) shows the cyclic tag system in the same form as on pages 95 and 96. Picture (b) shows the system with sequences on successive steps rearranged so that they do not shift to the left when the first element is removed. Picture (c) is a skewed version of (b) in which the way information is used from the underlying rules at each step is explicitly indicated. Picture (d) shows a more definite mechanism for the evolution of the system in which different lines effectively indicate the motions of different pieces of information.