This paper describes a workstation file system that supports a group of cooperating programmers by allowing them both to manage local naming environments and to share consistent versions of collections of software. The file system has access to the workstation's local disk and to remote file servers, and provides a hierarchical name space that includes the files on both. Local names can refer to local files or be attached to remote files. Remote files, which also may be referred to directly, are immutable and cached on the local disk. The file system is part of the Cedar experimental programming environment at Xerox PARC and has been in use since late 1983.