4.3.3.3 Inspection procedurea) The position of the first edge (x1) of the ferrule under test is recorded.b) The stage is moved so that the centre of the ferrule passes through the x-y marker until thesecond ferrule edge is reached. The position of the second edge is recorded (x2).c) The ferrule diameter is the difference between the two edges of the ferrule under test: .diameter of the ferrule = (x2 - x1).