I'm rather a novice. By split mainsheet do you mean a line from
the boom to Port through a block, and a line to starboard through
a block where you pull on one and release the other to control
the angle of the boom?
Yep, it's a 3:1 or higher purchase system run through blocks on the cabin roof, situated on either side of the companionway entrance. There's no mainsheet traveller. Pull one end, the boom goes that way, pull the other end, the boom goes this way, let both out on a broad reach or run. I've never used it, but that's my understanding.