FAT, an acronym for File Allocation Table, is a file indexing system that, among other things, allows for long file names.

Hoping to deep fry FAT, the Public Patent Foundation (PubPat) and David L. Hoffman requested separately that the patents covering FAT be re-examined in April 2004 (5,579,517) and January 2005 (5,758,352).

After hearing of the allowance, PubPat Executive Director Dan Ravicher blamed the patent office, whining that the ex parte reexam invocation procedure only provides one shot of input by the instigator, not continued mischief making.

Reversing non-final office action rejections of both patents after persuasive evidence by Microsoft, the patent office okayed the FAT twins once again.

Patents defended through reexam are generally considered invincibly valid. While not publicly stating whether it will cook FAT infringers, Microsoft can now merrily enforce these patents.

Linux uses FAT, and the licensing terms covering its distribution, known as GPL (General Public License), issued by the Free Software Foundation, forbids the distribution of programs that use patented technologies necessitating royalty payments. Wailing and gnashing of teeth have already been heard from politico Linux boosters. Further squirming from Linuxland is expected.