EXTEND

     EXTEND specifies the numbers of grid points beyond the GRDAREA which 
     define the grid extend area in the Barnes objective analysis.  The 
     first pass is computed on the extend area to reduce edge effects on 
     the GRDAREA.
 
     EXTEND is specified as four integers, which are the number of grid 
     points to extend the grid left, down, right, and up.  The values are 
     separated by semicolons.  The default for EXTEND is 2;2;2;2.