use the LAYER=BACK option on your draw statement to draw the elements on the back
layer.
For plots that have axes, if the graph wall area is filled (default), graphics elements that
are drawn on the back layer are obscured by the wall fill. To make the elements visible
in that case, include the WALLDISPLAY=NONE or WALLDISPLAY=(OUTLINE)
option in your layout statement. You can also use the TRANSPARENCY= option in the
plot statement to adjust the transparency of the graph in order to allow the graphics
elements underneath to show through.
For information about using the draw statements to add graphics elements to your graph,
see “Adding Graphics ...
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