Prior to AmigaOS 3.5, AmigaDOS file handles maintained a 32-bit wide offset parameter (unsigned), telling where to start the next read or write operation. The biggest size for any single Amiga file under these operating systems therefore comes to 2<sup>32</sup> = 4 [[gibibyte|GiB]]. After Amiga OS 3.5, file handles may reference 2<sup>64</sup> = 16 [[exbibyte|EiB]] files. However, OFS-formatted disks continue to retain the 32-bit limitations, for that is an intrinsic limitation of the format as recorded on the media.
An OFS datablock stores block size BSIZE-24 bytes (i.e. normally 488 bytes at most frequently used BSIZE of 512 bytes).
