National force standard machines can be split into two categories – those where the generated force is
calibrated against other force machines by the use of transfer standards and those where the generated
force is calculated from a mathematical model of the force generation system. For the first category, the
uncertainty of the force can be calculated following the guidance given in “5 Force calibration machines”.
This section deals purely with the second category which may include, but is not limited to, machines of the
following types: