Example circuit before and after D-type migration. A simple example of restructuring procedures where the contents of flip-flops change is shown in figure~\ref{fig:restruct1}. Both circuits compute the same logic function (assuming all clocks commoned) but they have vastly different timing properties. Compared with the right-hand figure, the left-hand figure has a later output but can accept later inputs. This form of restructuring is known as D-type migration or `<em>re-pipelining</em>'. Note that, in the figure, the number of D-types has actually changed. % .com-----------------------