Flooding recalculates the pour areaand recreates all clearances for the current obstacles within the pour outline,observing clearance rules. Hatchingrefills (with hatch lines) existing pourpolygons for the current session; it does not recalculate the pour area. Eachtime you open a design file, you must flood or hatchthe design; this information is not saved. In most cases, you can simply Hatch. Use Flood if you make changes to thecopper pour polygon that could create clearance violations or if you changeclearance rules.