Editing AmigaDOS (section)

=== Official variants of Amiga filesystems ===
'''Old File System'''/'''Fast File System'''
*OFS (DOS0)
*FFS (DOS1)
*OFS International (DOS2)
*FFS International (DOS3)
*OFS Directory Caching (DOS4)
*FFS Directory Caching (DOS5)

'''Fast File System 2 (AmigaOS4.x/MorphOS)'''
* OFS Long filenames (DOS6)
* FFS Long filenames (DOS7)

Both DOS6 and DOS7 feature International filenames featured in DOS2 and DO3, but not Directory Caching, which was abandoned due to bugs in the original implementation. DOS4 and DOS5 are not recommended for use for this reason.

Dostypes are [[backwards compatible]] with each other, but not [[forward compatible]]. A DOS7 formatted disk cannot be read on original Amiga FFS, and a DOS3 disk cannot be read on a KS1.3 Amiga. However, any disk formatted with DOS0 using FFS or FFS2 can be read by any version of the Amiga operating system. For this reason, DOS0 tended to be the format of choice of software developers distributing on floppy, except where a custom filesystem and bootblock was used - a common practice in Amiga games. Where software needed AmigaOS 2 anyway, DOS3 was generally used.