One of my abstractors sent me a copy of a discharge of mortgage that she came across, asking if I had ever seen anything like it.  The answer was no.  The answer was also no from the title examiner I asked from one of my favorite title companies here in Michigan.  Here's the interesting part:

.....document number 2006-032602 is discharged.  The debt secured by the mortgage described above has been partially paid.  Therefore, this discharge does not constitute a satisfaction of the debt.  Absent a separate agreement in writing providing otherwise, the debt remains in full force and effect.  This discharge serves only to release the lien of the mortgage upon the property described therein. 

Note that this is NOT listed as a Partial Discharge of Mortgage nor does it list the legal description.  It was recorded by MERS (Illinois), notarized in Arizona, for a Michigan mortgage.  Anyone have any answers?