d43df8b8_ehire__or_Interagency_Transfer__then_
[If…] you are correcting the employment date (ASSIGN DT) and/or position number (POSITION) for HØCUS Switch 4 [then…] 
any HNH rows that correspond to the old position number and/or old date will be deleted, and a new HNH row will be inserted. The appropriate HNP row to use is determined by the value that is entered in the HNP SW field. Valid values are S, V or D.
USPS Process Guide: Ch 4, HMPFX - Changing Information for a New Hire, Rehire, or Interagency Transfer
then…