toe the line

• toe the mark
• tow the line

Most likely derived from putting one's toe to a line, mark, or seam on a naval ship as a form of regimentation or punishment.

toe the line

1. (idiomatic) To abide by the rules or conventions.

   Television shows these days do not always toe the line of decency and common sense.

   • 1831, Captain Basil Hall RN, Fragments of Voyages and Travels, reprinted from the London Literary Gazette in The Atheneum, 4th series, volume 1, page 188:

     The matter, therefore, necessarily became rather serious; and the whole gang of us being sent for on the quarter deck, we were ranged in a line, each with his toes at the edge of a plank, according to the orthodox fashion of these gregarious scoldings, technically called ‘toe-the-line matches.’

2. (idiomatic) To stand at one's mark before a footrace.

   Alberto Salazar is one of the most famous athletes to have toed the line at this great race.

• (abide by rules or conventions): walk the line

• fall in line