What is the dress code at IIST, BITS and NIT-Trichy?

There is no dress code in BITS. One of my friends is from the Goa campus but I am pretty sure that things are the same across all three campuses. You can wear shorts and a t-shirt to the class.

In NIT Trichy, this depends on the professor whose class you're attending and depends on which year you are in. According to the classification –

• In your 1st year, almost all professors will try to make you wear formals at the beginning of the year. 
• Slowly it'll reduce and they will only ask you to wear formal shirts at the very least.
• Most of the teachers do not mind T-shirts but some of them are really against it.
• In your 2nd, 3rd and final year you can just show up wearing casual pants and some shirts and T-shirts.

In IIST, you can wear whatever you want but it should be within the limits of decency as seen by the current society. So there are no strict rules regarding the dress codes.