Question

_______are markings used to identify an arrow.

Answer 1

Crest (equipment) – Heraldic markings on an arrow used for identification or design

Answer 2

Answer:

Index feather

Explanation:

Having only three feathers, their position can't be symmetric to the string. One stays, usually, at 90° from a side, this feather is commonly called "index pen". It usually has a different color from the other two so that it can be found as you see the arrow.