Microsoft suffers FAT patent setback

Microsoft's FAT file system patent runs into difficulty

The US Patent and Trademark Office (PTO) has rejected two patents relating to Microsoft's control of the FAT file system.

File Allocation Table was developed for MS-DOS and is the primary file system for Windows, and a popular format for floppy disks and other storage devices.

The PTO has rejected the application because of an "administrative technicality" on one of the applications in which incorrect names of assignees were used. It is now offering Microsoft more time to make corrections.

Microsoft said that it was granted a patent for FAT in 1996 and began licensing the system to third parties in 2003.

The ruling is being closely watched by open source advocates as a new patent could allow Microsoft to force any company selling software that is able to read and write FAT to license the technology.