Digress is a multipartite virus. When an infected file is executed, the virus will infect the MBR of the hard drive. After next boot, virus will load resident from the MBR and infect all accessed COM and EXE files that are shorter than 64kB or so.
Digress was reported to be in the wild in the USA in September 1995.
Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.
Technical Details: Analysis based on report by Paul Glanville