Question: what is a chain in surveying?
Answer: The chain is a unit of length equal to 66 feet (22 yards). ... There are 10 chains in a furlong, and 80 chains in one statute mile. In metric terms, it is 20.1168 m long. By extension, chainage (running distance) is the distance along a curved or straight survey line from a fixed commencing point, as given by an odometer.