The erase24 geoprocessing operation is essentially the opposite of a clip. Whereas
the clip tool preserves areas within an input layer, the erase tool preserves only
those areas outside the extent of the analogous erase layer (part (f) of Figure 7.11
"Vector Overlay Methods "). While the input layer can be a point, line, or polygon
dataset, the erase layer must be a polygon dataset. Continuing with our clip
example, county managers could then use the erase tool to erase the areas of
private ownership within the county floodplain area. Officials could then focus
specifically on public reaches of the countywide floodplain for their upkeep and
maintenance responsibilities.