Invoice Amounts by Status pagelet (AP Operational Dashboard)

We are looking at the AP Operational Dashboard and deciding what pagelets we'd like to display.  But I'm having trouble finding information abou tthe Invoice Amounts by Status pagelet (a pivot grid).  In the prompts there is a field for a Date Option (options are Current Date or Ending Date) and a field for Ending Date.  Exactly what do these fields mean?  I assume the Ending Date field is to specify the ending date for the data you want to display, but what is the Date Option used for?  Both fields are required.  I've tried searching PeopleBooks but nothing comes