The so-called T+ 1 is the transaction confirmation time, t day is the trading day of your transaction, and T+ 1 day is the next working day of this trading day.
For example, it should be redeemed before today 15, T day is today, and T+ 1 day is tomorrow.
Whether it is t or 1, it is a working day, excluding weekends.
Let's see what others say.