I don't understand this graph. Wouldn't "no diploma" also include "no college" and "some college"? And wouldn't that mean that the line would be in between th

I don't understand this graph. Wouldn't "no diploma" also include "no college" and "some college"? And wouldn't that mean that the line would be in between those two rather than being longer? Or is this referring to no high school diploma? I'm also curious what the graph would look like if you included people who have Masters and PhDs.