How Can I pull the time period from MIS.GL.PERIOD on a BAR.REV.PROC report?

In the MEDITECH NPR DPM MIS.GL.PERIOD, there is an index (table) called date.x (Logical name: mis.gl.period.date.x).  The value of the table MIS.GL.PERIOD.date.x for the key BAR.REV.PROC.ending.date is the MIS.GL.PERIOD.period.