Background color

Most terminals allow you to set an explicit background color for the plot. The special linetype bgnd will draw in this color, and bgnd is also recognized as a color. Examples:

    # This will erase a section of the canvas by writing over it in the
    # background color
    set term wxt background rgb "gray75"
    set object 1 rectangle from x0,y0 to x1,y1 fillstyle solid fillcolor bgnd
    # This will draw an "invisible" line along the x axis
    plot 0 lt bgnd