The files created through use of the export and backup features in the DeltaV Continuous Historian have a file extension of .xfc and are saved in a directory of your choice. It is recommended that the export directory be on the same workstation as the DeltaV Continuous Historian, but outside of the DeltaV system directory. Because of the limited capacity of online storage, it is expected that you will transfer older .xfc files to a removable medium for permanent offline storage. Files may be brought back online as needed by using the Create Extended Dataset or Restore options in the Continuous Historian Administration application.
When different versions of DeltaV software are used to create these files, be aware that, in general, older .xfc files will be readable by versions of DeltaV software newer than the one that created them. They will not, however, be readable by versions of DeltaV software that are older than the version that created them. If you have more than one DeltaV system operating at different version levels, take this into consideration if you plan to move historical data between systems.