This standard specifies the basic tooth profiles of cylindrical worms. This standard applies to cylindrical worm drives with modulus m greater than or equal to 1mm and shaft angle ∑ equal to 90°. The basic worm types are Archimedes worm (ZA worm), normal straight profile worm (ZN worm), progressive Open wire worm (ZI worm) and cone enveloping cylindrical worm (ZK worm).