WDM-3A diesel passenger and freight locomotive of Indian Railways at Shantiniketan, India With approximately 1.6 million employees, Indian Railways is the country's single largest employer. Staff are classified into gazetted (Group A and B) and non-gazetted (Group C and D) employees. The recruitment of Group A gazetted employees is carried out by the Union Public Service Commission through exams conducted by it. The recruitment to Group 'C' and 'D' employees on the Indian Railways is done through 19 Railway Recruitment Boards which are controlled by the Railway Recruitment Control Board (RRCB). The training of all cadres is entrusted and shared between six centralised training institutes.