So it means that the army is step by step upgrading its t 72 to more modern variantAim was to integrate all the components. It was called Project Rhino or something I think. Poland and Czechs were being consulted. But things didn't happened that way.
So 1st came the original T72s. Then came T-72M1 with ERA. Then Indian Army realised that night fighting is an issue so TI started coming in. Then other things.