FS (File System)
The file system services support the creation and access of a UOS file system within a file. All File System services start with FS$.
A file system file is a file store that contains a complete UOS file system. A new file system can be created in a new file and various file system operations can be performed on the file system in the file. The FS$Open service opens an existing file system file, or creates a new one, and returns an integer context which is used by other FS$ service routines. When done with a file system file, the FS$Close routine should be called. For clarity, a reference to the "FS File" indicates the file that contains the file system within a file. "File system file" indicates a file within the FS File's file system.