SCO, Xenix and Coherent are commercial Unix systems for Intel machines, and Version 7 was used on the DEC PDP-11. Saying Y here would allow you to read from their floppies and hard disk partitions. If you have floppies or hard disk partitions like that, it is likely that they contain binaries from those other Unix systems; in order to run these binaries, you will want to install linux-abi which is a set of kernel modules that lets you run SCO, Xenix, Wyse, UnixWare, Dell Unix and System V programs under Linux. It is available via FTP (user: ftp) from <ftp://ftp.openlinux.org/pub/people/hch/linux-abi/>). NOTE: that will work only for binaries from Intel-based systems; PDP ones will have to wait until somebody ports Linux to -11 ;-) If you only intend to mount files from some other Unix over the network using NFS, you don't need the System V file system support (but you need NFS file system support obviously). Note that this option is generally not needed for floppies, since a good portable way to transport files and directories between unixes (and even other operating systems) is given by the tar program ("man tar" or preferably "info tar"). Note also that this option has nothing whatsoever to do with the option "System V IPC". Read about the System V file system in <file:Documentation/filesystems/sysv-fs.txt>. Saying Y here will enlarge your kernel by about 27 KB. To compile this as a module, choose M here: the module will be called sysv. If you haven't heard about all of this before, it's safe to say N.