Remachining is used to automatically mill regions that were not cut by previous operations. Remachining can be performed with or with a parallel, Z finish or 3D spiral toolpath. There is also a separate type of toolpath that is strictly for remachining called corner remachining.
How to create a remachining operation
See also Surface manufacturing, Recommended Machining Strategies, 3D Milling tab and Manufacturing attributes, Pencil milling and 3D leads/step tab.