If you are an educator, encourage your institution to purchase a set of historic IS codes from BIS. If you are a practitioner, budget for code purchases like any other tool. If you are a student, use your library privileges. Together, we can build legally and ethically.
The Indian Standard code IS 456:1978 (Code of Practice for Plain and Reinforced Concrete) is an older version of the standard that was largely superseded by IS 456:2000
To summarize:
Therefore, . It is a historical document that was superseded over two decades ago.