Error values are bound through the ErrorBar.binding property or set to an object with 'plus' and 'minus' values.
The value property represents the error as an absolute value.
The value property represents the error as a percentage.
The value property represents the error as a number of standard deviations.
The error is the standard error of the mean (value property is not used).
Specifies the meaning of the ErrorBar's ErrorBar.value property.