You are looking at this section:
4.1.9 The “electronic switch” module (Electronic switch)
It's the "Electronic Switch Module" not the "Sample and Hold". I too think it's not clear.
If you look at the picture "The electronic switch" in the section, then you can see the letters "A" and "B". It's possible to see what connections that are.
You are right it's hard to see what "C" is. The letter is not there. But if you draw a straight line down from "A" thru "B", then the next connection you hit is connection "C". A orange line go straight down to it. Would be nice if the letter "C" was there.
Hope this help to clarify.