load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"

begin
  wks = gsn_open_wks("ps","poly2b")     ; Open "poly2b.ps" file

  mpres              = True             ; Map resources desired.

  mpres@mpMinLatF    = 25               ; Zoom in on United States.
  mpres@mpMaxLatF    = 50
  mpres@mpMinLonF    = 235
  mpres@mpMaxLonF    = 290

  map = gsn_csm_map(wks,mpres)          ; Call gsn_csm_map to draw a map.
end