TH2D RMS x and RMS y meaning?

[Thomas_Parker]

I have created a 2 dimensional histogram (TH2D) with about 9000 entries. On the legend, the figure displays the mean x, mean y, RMS x and RMS y. I was just wondering if RMS x and RMS y refer to the standard deviation of the x values and y values, as is the case for the TH1D class?

[couet]

Meaning/Significance of RMS

I know that the rms value in the Statistics box stands for the root mean square, and I know the formula for rms. But, I am not sure what it means when the Statistics box displays RMSx and RMSy. Does it represent the rms for each bin in x,y? I also read that in ROOT, the RMS actually is the standard deviation http://root.cern.ch/root/html/TH1.html#TH1:GetRMS. Is this true? Any explanation would be greatly appreciated. Thanks.