Thank you all. It's TREAS 310 Entry Class Code: PPD. March 24, 2022. I believe it's in response to my filing new client's 2019 and 2020 tax returns, which IRS might process later, but for now credited him with the first stimulus payment for him and his dependent son? That might explain a partial round-number $1700 refund. Maybe PPD means partially paid 🙂