-for Incremental and Differental backup by comparing the creation and modification
-times of the file to the time the last backup completed. If one of those two times
-is later than the last backup time, then the file will be backed up. This does
-not, however, permit tracking what files have been deleted and will miss any file
-with an old time that may have been restored or moved on the client filesystem.
+for Incremental and Differental backup by comparing the change (st_ctime)
+and modification (st_mtime) times of the file to the time the last backup completed.
+If one of those two times is later than the last backup time, then the file
+will be backed up. This does not, however, permit tracking what files have
+been deleted and will miss any file with an old time that may have been
+restored or moved on the client filesystem.