GST exemption for government services extended to water, public health, sanitation and slum upgradation; railway entity added to related entries. Amends Notification No. 1136-F.T. to insert a new Table entry (serial 3B, Chapter 99) exempting services to a Governmental Authority for water supply, public health, sanitation conservancy, solid waste management and slum improvement and upgradation at nil rate, and to insert 'and the Ministry of Railways (Indian Railways)' after 'Department of Posts' in the entries for serials 6, 7, 8 and 9; effective from 20 October 2023.