The box width and height are determined from the x and y errors in the same way as they are for the xyerrorbars style -- either from xlow to xhigh and from ylow to yhigh, or from x-xdelta to x+xdelta and from y-ydelta to y+ydelta , depending on how many data columns are provided.
If filled-box support is present, then the interior of the boxes is drawn
according to the current fillstyle. See set style fill (p. ) and boxes (p. ) for
details. Alternatively a new fillstyle may be specified in the plot command.