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

begin
;---Generate dummy vector data arrays
  M  = 30
  N  = 25
  PI = 3.14159

  V = 10.0 * cos(onedtond((2.0 * PI / M) * ispan(0,M-1,1),(/N,M/)))
  U = 10.0 * cos(onedtond((2.0 * PI / N) * ispan(0,N-1,1),(/M,N/)))
 
  U!0 = "x"   ; Name U's dimensions so we can transpose it
  U!1 = "y"
  Ut  = U(y|:,x|:)

  wks   = gsn_open_wks ("png", "veceff")       ; send graphics to PNG file

  res                     = True

  res@vcMonoLineArrowColor = False
  res@lbOrientation        = "Vertical"

  res@vcRefAnnoBackgroundColor = "White"
  res@vcRefAnnoFontColor       = "black"
  res@vcRefAnnoArrowLineColor  = "black"
  res@vcRefAnnoArrowUseVecColor = False

  vector1 = gsn_csm_vector(wks,Ut,V,res)


  res@vcMonoLineArrowColor  = True        ; Multi-colored vectors

  res@vcRefAnnoString1      = "0.40E+03"  ; Change the number in the box
  res@vcRefAnnoString2      = "Dummy ref box"
;  res@vcRefAnnoString2On    = False       ; Remove "Reference Vector" text
  res@vcRefAnnoParallelPosF = 0.          ; Move reference box to the left
  res@vcRefAnnoJust         = "CenterLeft"

  res@vcRefAnnoBackgroundColor = "black"
  res@vcRefAnnoFontColor       = "white"
  res@vcRefAnnoArrowLineColor  = "white"

  vector2 = gsn_csm_vector(wks,Ut,V,res)

  overlay(vector2,vector1)
  draw(vector2)
  frame(wks)

end