Our system has to create an ascii batch file to send data to another system. That system defines the first field of the record (PATNO) as Numeric with a length of 7. The PATNO itself is 6 digits followed by either a MOD 10 or MOD 11 self check digit. I've never done any of that, so I am hoping for some pointers on how I do a MOD 10/11 check digit. Is it a routine I run on the 6 digit number? Any help greatly appreciated.