FLT CREW OF A319 RECEIVE INCORRECT TOGW FROM ACARS WT MANIFEST. SHOWED TKOF GROSS WT LESS THAN ZERO FUEL WT.

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WE WERE ASSIGNED RWY 32L INTXN T10 FOR TKOF BY ORD GND CTL. FO PULLED UP NEW RWY PERFORMANCE FOR THIS RWY/INTXN SINCE WE WERE ANTICIPATING BEING ASSIGNED RWY 4L. WE HAD ALREADY RECEIVED OUR FINAL WT MANIFEST. THE FO ONLY INPUT THE RWY CODE (32LK) FOR A RWY 32L T10 TKOF AND LET THE ACARS SYS AUTOMATICALLY FILL IN THE REST. WHAT CAME BACK WAS RWY PERFORMANCE FOR A TKOF GROSS WT 2200 LBS LESS THAN OUR ACTUAL ZERO FUEL WT. OUR CORRECT TKOF GROSS WT WAS 116.8 LBS AND OUR CORRECT ZERO FUEL WT WAS 103.4 LBS. WHAT CAME BACK ON THE ACARS WAS A ZERO FUEL WT OF 103.4 (CORRECT) AND A TKOF GROSS WT OF 101.2 (2.2 LESS THAN ZERO FUEL WT AND 15.6 LESS THAN ACTUAL TKOF GROSS WT!). THE ONLY THING THAT I CAN THINK OF THAT CAUSED THIS WAS THAT THIS ACFT HAD THE ATSU TYPE ACARS SETUP AND IT PUTS IN THE ACFT WT TAKEN FROM THE FMGC. IF THE FO HAD MISTAKENLY PUT IN THE WRONG ZERO FUEL WT IT COULD HAVE CAUSED AN ERROR. HOWEVER; MY FO SWEARS HE DIDN'T PUT IN THE WRONG ZERO FUEL WT AND THE GROSS WT ON THE LOWER ECAM SHOWED CORRECTLY AND WE NEVER GOT AN ERROR MESSAGE THAT WILL OCCUR WHEN THE GROSS WT IS OFF BY OVER 10000 LBS. IN OUR CASE; SINCE WE WERE SO LIGHT; THIS WASN'T A SERIOUS PROB AS OUR RWY LIMIT FOR A REDUCED THRUST TKOF WAS 133.4 LBS AND SINCE OUR REAL TKOF GROSS WT WAS 116.8 LBS USING THE PERFORMANCE DATA IT GAVE US WAS NO PROB. HOWEVER; IF THIS WERE TO HAPPEN TO A FLT THAT IS UP AGAINST ITS RWY LIMIT; IT COULD BE A SERIOUS SAFETY ISSUE.