[–] Tsilent_Tsunami 0 points 1 point 1 point (+1|-0) ago (edited ago)
"Toe the line" is an idiomatic expression meaning either to conform to a rule or standard, or to stand poised at the starting line in a footrace. Other phrases which were once used in the early 1800s and have the same meaning were toe the mark and toe the plank.
From military experience, our physical version of toeing the line was to literally place our toes (while inside our boots) on a line painted on the ground.