There is a legend: a long time ago, Lu Ban taught his disciples to make round tables and square tables, but his disciples could never make circles or squares. So, ask the master. Lu Ban smiled and said nothing, and took out two things for this disciple. After a while, the apprentice made two very decent wooden round tables and square tables. So those two things are rules and regulations. Gauges are compasses used to draw circles; Moment is equivalent to a folding ruler, which can draw straight lines and right angles and measure the length. As the saying goes, no rules can't make Fiona Fang.