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Microsoft's FAT Patent Rejected

The U.S. Patent Trademark Office has rejected all claims to patents for a Windows file format held by Microsoft.

Under a reexamination process initiated earlier this year by the recently formed Public Patent Foundation (PUBPAT), The USPTO rejected all claims of Microsoft's technology, which includes its internally developed FAT Allocation Table (FAT) file system . The FAT file system is one of the technologies Microsoft has placed in its royalty-bearing licensing portfolio.

The patents came under scrutiny after critics claimed that the licensing policy was the beginning of Microsoft's efforts to shut down Linux. Linux support for FAT32, used in today's systems, started with the 2.0.34 kernel.

"The Patent Office has simply confirmed what we already knew for some time now, Microsoft's FAT patent is bogus," Dan Ravicher, PUBPAT's executive director, said in a statement. "I hope those companies that chose to take a license from Microsoft for the patent negotiated refund clauses, so that they can get their money back."

In its defense, Microsoft said it had not claimed control over the entire FAT system, but only over the technology that has been built up around the original code.

"We have some rights, but no one person has firm, strong control over all aspects of FAT," David Kaefer, director of business development for Microsoft's intellectual property and licensing unit, told the Associated Press.

The ruling is just the first step in a very lengthy process. Microsoft now has a few months to appeal the USPTO decision as part of what's known as "patent prosecution," a process to determine whether the patent should stand. The Patent Office examiner will look at the response and may modify the ruling. At that point Microsoft has the opportunity to respond to that. Then when the examiner makes a final ruling. Microsoft has the right to take its case to the U.S. Supreme Court. Analysts say patent prosecution can be a process as lengthy as the appeal of a patent infringement case.

However, Ravicher said third party requests for reexamination, like the one filed by PUBPAT, are successful in having the subject patent either narrowed or completely revoked roughly 70 percent of the time.

What is FAT File?

The FAT file system is used to keep track of the location and sequence of specific files stored on a PC's hard drive, a floppy disk or a flash memory card. Most operating systems store computer files by dividing the file into smaller pieces and storing them in separate clusters. The FAT file system, first developed in the 1970s by Bill Gates, lets the OS keep track of each file within the clusters and identify unassigned clusters for new files.

When a computer user wants to read a file, the FAT file system reassembles each piece of the file into one unit for viewing. Microsoft explained that the FAT file system was based on the BASIC programming language and was developed to allow programs and data to be stored on floppies.

Microsoft describes its patent as "the ubiquitous format used for interchange of media between computers, and, since the advent of inexpensive, removable flash memory, also between digital devices."

The license covers four patents:

  • 5,579,517: "Common name space for long and short filenames"
  • 5,745,902: "Method and system for accessing a file using file names having different file name formats"
  • 5,758,352: "Common name space for long and short filenames"
  • 6,286,013: "Method and system for providing a common name space for long and short file names in an operating system"

All four of these patents deal with the virtual FAT , a system driver that acts as an interface between an application and the system's FAT. One of the limitations of the FAT file system technology is that it can store only files with eight-letter words; VFAT allows for the longer file names commonly used to today.

Pricing for the Fat file system license has been set at 25 cents per unit, with a cap on total royalties of $250,000 per manufacturer. The 25 cents per unit fee is available for devices that use removable media to store data, including PDAs, digital cameras, digital camcorders and portable digital audio players.

Even if Microsoft were to levy a charge against everyone -- not just the manufacturers, as it does under the current licensing policy -- it would only affect the use of VFAT technology.

Companies that wanted to continue using FAT and avoid the license fees could do so by taking out the VFAT system driver and forcing customers to come up with eight-letter filenames.