Can someone please tell me the logic the program PRC: Generate Cost Accounting Events uses to determ

The reason I am asking is because we generated the cost accounting events and in the output the expenditure_date, which I am assuming is the accounting event date was Aug 01st.  But when we then ran the create accounting with an End-Date of July 31st, this event was picked up and it showed an event date of July 31st.  Don't know why the two outputs would show different dates unless the output of the generate cost accounting events isn't showing the accounting event date.