Microsoft describes the FAT file system as "the
ubiquitous format used for interchange of media between computers,
and, since the advent of inexpensive, removable flash memory, also
between digital devices." In general terms it allows an operating
system to locate and collate files stored on a computer disk or
memory card.
The software giant was granted the patent in 1996 and in
December 2003 announced that the main FAT patent (the ‘517 patent)
and three other related patents were to be included in a new
licensing portfolio.
But the Public Patent Foundation (PubPat), which lobbies against
the current patent system, questioned the company's motives,
speculating that the fact that the portfolio did not include
licenses for use in free and open source software meant that
Microsoft intended to use its patents to fight the competitive
threat posed by free software.
Microsoft might, so the argument goes, be able to charge free
and open source software developers for the use of the FAT
technology – hitting the community hard because the use of any
royalty dependant software is prohibited under the open source GPL
licence.
In April last year PubPat filed a formal request with the US
Patent and Trademark Office to revoke the patent. The lobby group
submitted evidence of prior art – that the feature being patented
was already in the public domain – and achieved some success when
the USPTO issued a preliminary rejection of the patent in September
2004.
The re-examination process has now moved forward a step or two
further with, in a decision released this week, the USPTO again
rejecting the ‘517 patent and issuing a preliminary rejection for
the related ‘352 patent.
However, the rulings were not based on the prior art claims.
According to reports, the USPTO found the patents invalid only
because of a technical discrepancy over who should have been listed
as inventor.
Microsoft is planning to fight on.
