The objects that can be shared through NFS include any whole or partial directory tree or file hierarchy--including a single file. However, a machine cannot share a file hierarchy that overlaps one that is already shared, and peripheral devices such as modems and printers cannot be shared.
In most UNIX system environments, a file hierarchy that can be shared corresponds to a filesystem or to a portion of a filesystem; however, NFS works across operating systems, and the concept of a filesystem may be meaningless in other non-UNIX system environments. Therefore, the term resource is used throughout the NFS topics to refer to a file or file hierarchy that can be shared and mounted over NFS.