Yerrorbars

The yerrorbars (or errorbars) style is only relevant to 2D data plots. yerrorbars is like points, except that a vertical error bar is also drawn. At each point (x,y), a line is drawn from (x,y-ydelta) to (x,y+ydelta) or from (x,ylow) to (x,yhigh), depending on how many data columns are provided. The appearance of the tic mark at the ends of the bar is controlled by set errorbars.

    2 columns:  [implicit x] y ydelta
    3 columns:  x  y  ydelta
    4 columns:  x  y  ylow  yhigh

An additional input column (4th or 5th) may be used to provide information such as variable point color.

See also http://www.gnuplot.info/demo/mgr.htmlerrorbar demo.