15.58.9  ERRORS 

This selects plots with or without error bars.  ERRORS=OFF  plots  without
any  errors,  while  XERRORS=OFF  only  omits the X error bars.  Similarly
YERRORS=OFF or ZERRORS=OFF omit the Y or Z error bars.
(Default:ERRORS=ON)

If  you  wish  to modify the appearance of the error bars see the command:
SET BAR.  This modifies the size of the bar at the end of the errors.

If the negative error bars are defined they are subtracted from the data.