>Try 'tow a line'.
Try google:
http://en.wiktionary.org/wiki/toe_the_line
In modern usage, this is sometimes carelessly written tow the line, which itself has taken on a new meaning as an eggcorn. This practice probably originated with people who heard the expression but were not familiar with the original spelling or meaning. With the spelling tow the expression naturally takes on a slightly more active meaning: not simply conforming to the rules, but helping to enforce or confirm them.