Stop a job nest that has not ended — queued, running, or kept as a draft. By default (apply=false) this only reads the job nest and says whether it can be cancelled and what cancelling does. apply=true (needs parts:write) cancels it: the materials and thicknesses already nested keep their result, the others are cancelled, and every remnant it holds goes back to stock. Cancelled before any material and thickness is nested, it gives its run back to this month's allowance; once one is nested, it counts as a run. A draft is discarded. A job nest that has ended (solved, failed or cancelled) is not cancelled again.