# Interpretation of a CLs exclusion plot

I have some trouble with the interpretation of this plot. The plot on the right shows the CLs values for the SM Higgs boson hypothesis as a function of the Higgs boson mass in the range 110–145 GeV. I understand that the background-only expectations are represented by their median (dashed line) and by the 68% and 95% CL bands, but I don't understand the red lines with values: 95%, 99% and 99.9% what are for.

Can somebody help me?

The horizontal red lines allow us to read off the Higgs mass ranges for different CLs. Looking at where the (black) data line crosses the horizontal red lines in the right hand figure, we can see that the 95% CL Higgs mass range is (roughly) $$122$$ to $$126 \frac{1}{2}$$ GeV, the 99% CL range is $$121\frac{1}{2}$$ to $$128$$ GeV, and the 99.9% CL range is $$120\frac{1}{2}$$ to $$129$$ GeV.