The Roast tab is similar to the Weigh in that it tracks batches created on the Batch page. Roast batch values shown reflect green coffee batches prior to roasting, or what needs to go into the roaster.
Roast has a couple main differences, though. A small difference is that Roast is sorted by roast level, from lightest to darkest based upon weight loss, rather than by green used.
A more significant difference is that you can create carryover by marking a roast as complete. We treat marking a roast as done as meaning it's really been roasted, and you can't go turn roasted coffee back into green.
It's for this reason that if you want to create Carryover, possibly for another Production Run to consume, you'll need to mark all the relevant Roast tasks as complete.
As an example, marking a 20lb batch with 20% weight loss as done for a production run that fulfills orders for just two 5lb bags of that roast would result in 6lbs of carryover to be immediately available - even if not every task on the production run is not complete.