This Supplementary Code relates to B3.1.1.01- Mechanical Code Of Practice, Section 3.26 - Wheelsets. It contains NZ Railways Mechanical Branch Code No 4 -Wheel Centres, Issue 3 of 1/5/1947; NZ Railways Mechanical Branch Code No 15 -Wheels, Wheel Centres and Tyres, Issue 4 of 1/6/1972, which contain information relevant to wheels, wheel centres and tyres.