PRESET                   Draw Point on Screen

 PRESET [STEP] (x,y) [,color]

    Plots a point at a specified screen location.

        STEP    If included, coordinates are relative to last graphics
                point referenced. If omitted, coordinates are absolute.

     x,y  Screen coordinates.

       color    Specifies the attribute of the point to be plotted. If
                color is omitted, the point is plotted in the background
                color.

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      Notes:    PSET is exactly the same statement, except that it plots
                by default in the current foreground color.