In the PingPlotter Manual, I attempted to find out what the vertical red bars indicate on the summary graphs. Unfortunately, the closest I could find was this: http://www.pingplotter.com/manual/theinterfacegraphs.html but that talks about the red line that jumps from hop to hop. The page in the manual that specifically addresses the Summary graphs doesn't discuss it (or I missed it, which is possible.)

What, exactly, does the vertical red bar in the Latency column indicate in the summary graphs and how do you determine its value (what's the scale, etc.)?

I would also suggest adding a Key to every single page, initially collapsed to minimize space used, which provides a simple explanation for any graphical item that does not have an explanation when you hover over it, such as the blue X, the red bar, the black line with start and end marks, etc.