User interface > Transformation of groups of files > Transformation manager > Transformation options > N:N Transformation > Backup
If by the transformation existing files are overwritten, then it is advisably to make a backup of them before. There therefore is the possibility in the options of the transformation manager of selecting a folder into which the original files are copied before the transformation.
Even if the backup option is activated, a backup is made only, if at least one file will actually be overwritten. In this case all source files are saved.
Before a transformation starts, it is checked whether, source files will be overwritten. If this is the case and the backup option isn't set, a warning appears which still permits to let make a backup of the the original texts.
By the roll back function the backup files can be copied back, as long as the settings weren't changed in the transformation manager.
Remark: If the path and the name of a target file are identical with those of the source file, the result of the transformation will first be written into a temporary file, which will be renamed to the original name, if the transformation succeeds. If an error occurs, the temporary file will not be renamed and is left in the target directory. You can look at it in an editor and see where the error occurred. The names of the temporary files are constructed of temporary, eventually followed by a number and with the extension tmp.