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.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago