When processing an HR Change Form, you can find a list of Action and Reason codes in a setup table in PeopleSoft. 

Navigate to Action and Reason Codes

Click on Main Menu > Set Up HRMS > Product Related > Workforce Administration > Action Reasons

Find Action and Reason Codes

1. In Action Reasons, to the right of Action, clickand a list of Action Codes will appear in a pop up
   
2. To see the Reason codes for an action, in the pop up, click the action
3. Back in Action Reasons, click Search and a list of Reason Codes (with descriptions) for that action code will appear below