The Indian railways are broadly divided and sub-divided into zones, divisions and departments, each controlling a particular function. Every division has a certain number of technical and non-technical departments, which form the base structure on which the railways function.
Technical departments include civil, technical and mechanical engineering, signalling and telecom, and several others dealing with similar disciplines. The non-technical departments include general services such as Accounts, Personnel Management, Railway Protection Force (RPF) or Security and Traffic Services, among others.
Each department has staff at various levels. The highest are the Group A officers, while the lowest in rank are the Group D staff members.