Sets or returns whether the error bars will be T shaped.
If the error bar is not T shaped, it will consist of a single line going from the negative error value to the positive error value. If the error bar is T shaped, there will be an additional line perpendicular to this line at each end of the error bar. All parts of the line, including the T, are formatting according to the ErrorBar.Line property.
If you create a new error bar with ExcelWriter, it will be T shaped by default.