a "logical sector number" formula in the ecma-107 and iso/iec 9293:1994 (superseding iso 9293:1987) standards for fat file systems matches exactly the lba formula given above: "logical block address" and "logical sector number" (lsn) are synonyms. the formula does not use the number of cylinders, but requires the number of heads and the number of sectors per track in the disk geometry, because the same chs tuple addresses different logical sector numbers depending on the geometry. examples: