The present invention relates to method and apparatus that recordsreproduces data tofrom an optical disk to rearrange user data such as video andor audio data or to restore original data order by scanning each ECC block in a U-pattern. An optical sensor has a field of view of at least a portion of the tracking surface during movement of the displaceable member in the operational zone and generates optical data in response to light received from the tracking surface. Each valve has two additional ports in its valve body, positioned such that when the plug is closed, both ports are open to the valve bore, and when the plug is open, at least one of the ports is open to the bore. Thus, the common rail pressure during an injection period is smoothed. This etching obtains a milky-dull color uniformly on the surface.