Bank Reconciliation- How is Reconciliation Difference calculated

How is Reconciliation Difference calculated? 

Bank Reconciliation 

The Reconciliation difference amount is derived from the calculations below.

Bank Balance - Total Outstanding = Reconciliation Balance

GL Book Balance - Reconciliation Difference = Reconciliation Difference

Bank Balance is manually keyed when the reconciliation is generated.

GL Book Balance is the balance of the GL accounts tied to the noted bank code through the end of the reconciliation range defined on the Bank Reconciliation Record.