Bert,
The VC200L is a variation on the Dall-Kirkham design - corrector is combined with the sperical secondary, the other oddities about this tube are a non-spherical primary formed by the coating process and a built in corrector/flattener (in the draw tube). Basically the scope is optimised for imaging and has a very flat field (attached is a corner crop of the full frame lagoon image fyi). More info here:
http://www.vixenamerica.com/Products..._or_Cat=VC200L