I think I've finally answered my own question. A marker is simply a hole
in the fabric. The outline of the hole is the marker points, which seem
to draw things upside down since upper left is 0,0. If you use a
markerPattern you have a tiled sheet behind these holes in the fabric that
show through. Apparently the idea of using an image as a marker was a
misconception. The marker color and the marker fill color can be
established from the marker level of the graphic dialog box. If you keep
the line width at 1 or 2, you can create little icons that appear at the
points of the polygon. You can define closed, disconnected areas inside
the outer perimeter of the marker by leaving a gap in the pointers, but I
found no obvious way to keep the markerFill out of these internal areas.
The markers don't scale as you scale the graphic itself. If you wanted to
scale markers, I guess you would need to modify the markerPoints.
If some of this is incorrect, someone please get out the red ink. If it
helps someone else unravel some of the marker mystery, great.
Sincerely,
Clark P