Is there any documentation/description available for the N-O file system [OFS] structure, without reading the source code files ? Using Partitions.ShowBlocks I can see that: - the directory starts at block 1032, - each entry is 40 bytes wide, - they are [re]arranged alphbetically by fileID, - the 'table' starts: 00: <4 bytes> <number of dir-entries> 10:<32 chars for 1st file ID> <8 bytes= 2 words> seemingly only the 1st word after the ID-field is used? Simplistically this would be an offset ? But when I re-formatted [which I later discovered does NOT delete/reset previous bytes] and entered 4 'new' files: one, two, three, four, of sizes as below, I see: FuleID arg-word File-size Dif-words =============== use const width font to view=== one 5829 75 29 two 5858 75 29 three 5887 75 29 four 5916 115 29 So the [apparently redundant] word-val 29 is independant of the file size ? In fact for a big-directory all the 'arg-words' are multiples of 29; and the 1st chronologically entered File's arg-word: 5829; equals 201*29. Thanks for any feedback, == Chris Glur. PS. yes you guessed that I want to recover some lost valuable files.