The arrow appears to have been done by hand when the glass was still hot. The pictures aren't great; I'm using an old digital camera and the lighting is bad. I don't know what the purpose of the arrow was. It visually aligns between the T and A in Whitall. I had a 154 Dominion in orange amber with the same type of marking. I didn't take any photos of it though. I traded it and cash to Gene Hawkins at the 2020 Beat the Winter Blahs.