Wow...um...Yes??
The mark on the curve will have all of those....
Let me try it this way....Visually I see that there is a "problem" sometimes I am unsure of what it is. I use the "mark" as a place holder. It helps me to return to the exact point(s) on the curve where the trouble is, It used to be a point source but in reality it is a range. Mike added the "worms" so that you could see what is really being effected.
http://www.curvemeister.com/wiki/index.php?title=Color_WormsI mark the curve where I know there is a problem so I can go there without having to guess exactly where it was only seconds ago.
One way to get a better view of this is to use the floating hue clocks. Take the gorge picture and alt-click on the image in the backwater. A Hue clock will appear with a line to the point you selected. This is coming up in future lessons, but you are asking such a good question I wanted to bring it out for you...
So what do you do with this fine Hue Clock...You can use it to determine a few things very quickly. It tells you the exact value at that selected point. Typically a sample of 5X5 pixels. This is adjustable. I keep mine at that (5X5) or less depending on the area I am working on. It can tell you what direction your changes need to go. It gives you the intensity of the color. If you want to control the color of a few different areas it can show you the effect of a change in one place on a different part of the image. You can have as many Hue clocks as you want. It is very interesting to watch what happens to the various areas when you have multiple hure clocks open.
Each selected point will have a different Slope, Width, and Location on the curve....
Greg