[open-cobol-list] About the Overflow

[Peg]

Hello All,
Expecting it doesn't result when the overflow was tested.
Is my expectation wrong? or, this is bug?

--------------------------------------------------
 IDENTIFICATION DIVISION.
 PROGRAM-ID. TESTFLOW.
 DATA DIVISION.
 WORKING-STORAGE SECTION.
 01 DATA1 PIC 9(2) VALUE 5.
 01 DATA2 PIC 9(2) VALUE 5.
 01 DATA3 PIC 9(2) VALUE 1.
 01 DATA4 PIC 9(2) VALUE 1.
 01 DATA5 PIC 9(2) VALUE 99.
 01 DATA6 PIC 9(2) VALUE 99.
 PROCEDURE DIVISION.
 COMPUTE DATA1 = DATA1 - 1.
 DISPLAY "COBOL85:04 MicroFocus:04 | " DATA1.
*
 SUBTRACT 1 FROM DATA2.
 DISPLAY "COBOL85:04 MicroFocus:04 | " DATA2.
*
 COMPUTE DATA3 = DATA3 - 3.
 DISPLAY "COBOL85:00 MicroFocus:02 | " DATA3.
*
 SUBTRACT 3 FROM DATA4.
 DISPLAY "COBOL85:00 MicroFocus:02 | " DATA4.
*
 COMPUTE DATA5 = DATA5 + 5.
 DISPLAY "COBOL85:99 MicroFocus:04 | " DATA5.
*
 ADD 5 TO DATA6.
 DISPLAY "COBOL85:99 MicroFocus:04 | " DATA6.

$ cobc TESTFLOW.COB -free -std=cobol85
$ ./TESTFLOW
COBOL85:04 MicroFocus:04 | 04
COBOL85:04 MicroFocus:04 | 04
COBOL85:00 MicroFocus:02 | 02  <--- NG?
COBOL85:00 MicroFocus:02 | 02  <--- NG?
COBOL85:99 MicroFocus:04 | 99
COBOL85:99 MicroFocus:04 | 99

$ cobc TESTFLOW.COB -free -std=mf
$ ./TESTFLOW
COBOL85:04 MicroFocus:04 | 04
COBOL85:04 MicroFocus:04 | 96  <--- NG???
COBOL85:00 MicroFocus:02 | 02
COBOL85:00 MicroFocus:02 | 02
COBOL85:99 MicroFocus:04 | 04
COBOL85:99 MicroFocus:04 | 04
--------------------------------------------------

Environment : Windows(Cygwin 1.5.17 gcc 3.3.3)

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