Microsoft has started a campaign to license all implementations of "FAT", the filesystem type used in MS-DOS. This filesystem format is used all over the place, including most media interchange by flash memory cards, USB-based "memory disks", and more. It is also used for floppy interchange on all operating systems that support floppy drives, including the open-source operating systems like Linux and the BSD family (including OpenBSD). Since Microsoft have refused to offer a no-fee license to open source groups, it could easily be inferred that they are trying to use the Patent Office to put an end to the challenge they face from open source development, and in the process put the lid they have always wanted on all software innovation other than their own. One of the leading groups fighting this effort is the Public Patent Foundation; please check out this information on their intervention filed with the U.S. Patent Office to re-examine Microsoft's claim based on prior art. See also my history pages for where Microsoft originally got MS-DOS from.