South African locomotive numbering and classification

The Union of South Africa was established on 31 May 1910 in terms of the South Africa Act, which unified the former Cape Colony, Natal Colony and the two colonised former republics, the Transvaal and the Orange Free State. One of the clauses in the Act required that the three Colonial Government railways, the Cape Government Railways, the Natal Government Railways and the Central South African Railways, also be united under one single administration to control and administer the railways, ports and harbours of the Union.

Source: Wikipedia — South African locomotive numbering and classification (CC BY-SA 4.0)