I’ve been reading Elmer Kelton’s The Day the Cowboys Quit. What does he mean by the word “tawline?”

I've been reading Elmer Kelton's The Day the Cowboys Quit. What does he mean by the word "tawline?" George Banks Jenks, Oklahoma A tawline was a term used in playing marbles. A “taw” was a shooter, and a “tawline” was the line the shooter stood behind. I figure it’s something akin to taking a stand: “when it comes to push and shove,” “drawing a line in the sand” or “when your back’s up against the wall.” Elmer Kelton was nice enough to respond to our query, and this is w