① It is necessary to perform 3-point leveling for reproducing the leveling in production.
② It is necessary to perform 3-point leveling for reproducing the accuracy of the
machine when it is manufactured.
③ As tilting occurs hardly at the time of installation, the leveling is made by 3-point
leveling.
④ If the leveling can also be made by four-point leveling and the accuracy can be
reproduced, it is unnecessary to perform 3-point leveling.