Just a short remark on “Linienanmerkungen”, the German translation of “Line annotation”.
An “Anmerkung” is a short explanation (written or spoken), so one always expects text with this word. Looking for hooks or arrows as an “Anmerkung” really feels strange. Unfortunately I can’t think of a clever expression at the moment. Perhaps something like “Linienergänzungen” (= “line additions”).
I’ll pass this feedback on.
How about „Linienanhang“?
But „Anhang“ mostly refers to something being added at the end.
A very simple translation would be to call it just an element: „Linienelement“
One last idea: „Lieniennotierung“ (more a line note)
This is a really hard one to translate, so I call for all the German speaking forum users to provide ideas. 
In Illustrator they are just called “Pfeilspitzen” (arrow heads) even if they can have any shape.
“Fischgräte” (fish bone) is also a quite creative translation of “chevron”.
Thanks, I’ll pass these on as well.