The flag variable column is added by Data Conversion (if you process data using Sea-Bird software) or ASCII In (if you are importing data that was generated using other software). The Loop Edit module sets the flag variable to bad for scans that show a pressure slowdown or reversal. The flag variable is then used by the rest of the SBE Data Processing modules as an indication of a bad scan, allowing you to exclude scans that are marked bad from processing performed in a module, if desired. Initially all scans are marked good (flag value of 0) in Data Conversion or ASCII In. A flag of -9.99e-29 indicates the scan has been marked bad by Loop Edit. Note: All occurrences of the bad value (-9.99e-29) can be replaced with a different value in ASCII Out. This may be useful for plotting purposes, as -9.99e-29 looks like 0 in a data plot.