Microsoft's contentious patent describing the mechanism used to store long filenames on FAT filesystems without breaking compatibility with old applications has been upheld by the German appeal court after a prior court decision ruled it invalid. This mirrors a 2006 decision by the USPTO concerning the equivalent US patent.

The German Federal Patent Tribunal claimed that the patent EP0618540 lacked the element of invention in 2007. The Tribunal stated that the work done on the Rock Ridge Interchange Protocol, which allows long file names to be used on the ISO9660 filesystem used on CDs, solved the same problem, and since Rock Ridge was developed in 1991, it predates the FAT long file name work.

The appeals court rejected this reasoning due to technical differences between the two systems, stating that Microsoft had to solve new problems that the Rock Ridge work didn't address. In particular, the way long names on FAT were designed so that legacy systems would ignore the new names was deemed to be significant.

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German appeals court upholds Microsoft Long File Name patent

Posted By: JMH
25 Apr 2010