TRatioPlot

Hi,
I would like to know what the dashed lines means in the TRatioPlot.
It is not explicitly mentioned. I assumed that the middle one is the mean and the two others are one sigma away from the middle one. Is that right ?
Thanks for your feedback.

The lines’ positions are defined with SetGridLines. The default values are determined in BuidLowerPlot according to the option chosen.