[CR]Reynolds 531 SL

Three questions:

1.) When did Reynolds come out with 531SL tubing?

2.) How do you know if your frame has it apart from special decals---in other words is it possible a frameset w/the 531DB label is actually made w/ 531SL tubing?

2.) Is 531SL the same tubing as the current 531 Competition?

Thanks,
Larry Hakim
Oxford, MS