Up: Set style rectangle
The yerrorbars (or errorbars) style is only relevant to 2-d 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.
A tic mark is placed at the ends of the error bar (unless set bars is
used -- see set bars (p. ) for details).