Edit/Save File Slack...
This function recovers a single file's slack space and saves it to a (text) file using a standard Save As dialog. Multiple files may be selected, but the resulting file slack file is usually not useful or complete. In some cases, this may help recover lost data which has been overwritten, but the user should not rely on this. Saving file slack as a text file may still result in some binary (eg. non-text) data.
See below for more information on file slack.
About File Slack
When Windows formats a hard disk, it uses the disk capacity to determine a cluster size - the minimum unit of disk space available for file storage. In most cases on NTFS file systems, this will be 4 kilobytes or 4096 bytes. This means that as file space is allocated to a saved file, the actual space used is stepped in 4 kilobyte increments. A 2 Kb file, for example, would still use (at least) 4 Kb of disk space. Checking a file's properties, shows that in every case (?) the size on disk is larger than the actual file size. Some of this disk space used is for attributes, security/permissions, etc., but in most large files, the majority of space is dedicated to actual file data.
But not all...! Since files - unless the size of data + attributes, etc. exactly equals a multiple of sector size - use disk space in 4 Kb increments, it is usual that some empty space in disk clusters exists. That empty space is not assigned to file data, or to attributes, security concerns, etc.; it is just wasted space and usually contains data left over from previous files which occupied the same clusters, or simply random memory bytes which were written with the file. That empty space (ie. file slack) could contain data placed there intentionally by malevolent programs, or could be used to hide data by the user. Programs such as Slacker can hide files within a file's slack space; interesting, but not a good idea unless you are sure the file size will not change or the file be erased.
The concept of file slack forms an important part of computer forensics - analysis of computer data for legal evidentiary purposes. An interesting short video on the possible use of file slack to learn more about a computer user can be found here on YouTube.
