Its a cascade style lift, just with the chains/belts ran internally. Its actually much like what our team is doing this year for a lift - it makes the sections extend simultaneously. This helps make it smooth with an equal motor load throughout extension, and also helps stability - as you have greater overlap across multiple extensions until you near your limit.
Check out slide 17 on this powerpoint from the workshops at championships last year - it shows the cascade and continuous systems drawn out side-by-side.
http://www.usfirst.org/uploadedFiles...ors_Needel.ppt