Until the release of DOS 5.0 in mid 1991, you normally needed to purchase a separate utility to recover deleted files, or to unformat a disk. Basically, these recovery programs allow replacement of the missing byte of information in the file name with a new character to make the file name complete in the root directory. This character may be, but does not have to be, the same character as it was before. The same process is available if a directory is removed. DOS treats subdirectories the same as files, when it is trying to locate them.
Recovery is as simple as described above.
An additional concern is now raised with the introduction of DOS 5.0. This upgraded version of DOS contains a number of utilities licensed from Central Point Software, the makers of PC Tools. Until recently, reformatting the disk was the simplest method for handling these concerns. This would make sure the disk was truly wiped clear of all data. However, with the introduction of DOS 5.0, this becomes a questionable approach at best, and perhaps even exacerbates the problem.