Spitball'n, but maybe this
Periodic Increment Date (PID)?
The periodic increment date is the date upon which an employee is scheduled to receive an increment increase by moving to a higher salary step within the salary range for his/her current class.
https://apps.leg.wa.gov/wac/default.aspx?cite=357-28-050
https://apps.leg.wa.gov/WAC/default.aspx?cite=357-28