I think it'd be reasonable to have a mark last for 6 months, then be cleared - assuming no new mark is added to it. In other words, someone gets a mark in March and goes through September (six months later) without incurring further violations, the mark is wiped. The slate is clean. Or, someone gets a mark in March, gets another in August of the same year, he's going to have to wait until February of the next year (6 months past the second mark) to have both marks cleared. Just tossing in that idea of one arrangement that might be considered.