Backup Files.

Whenever you make changes to a Project File (.MAK) or a Survey Data File (.DAT) the Project Manager or the Survey Editor makes a "backup" file from the unchanged data. Backup files have the same filename as the Project, except that the file extension is changed to ".BAK". For example, the backup file for GROANING.MAK would be GROANING.BAK. The purpose of these files is to protect you from editing errors. Unless you have made an editing error, you can generally delete backup up files.

If you have made an editing error, you can recover the original data from the backup file. You can do this by copying or renaming the backup file to the original filename and extension. Generally, you can copy or rename files using the Windows Explorer.