## Additional Information About Directories

The OS-9 directory system is very useful because it allows each user to privately organize files as desired (by project, function, etc.), without affecting other files or other user's files. Another advantage of the hierarchical directory system is that files with identical names can be kept on the same device as long as the names are in different directories. For example, you can have a set of test files to check out a program using the same file names as the program's actual working files. You can then run the program with test data or actual data simply by switching directories.

Here are some important characteristics relating to use of directory files:

- Directories have the same ownership and security attributes and rules as regular files.

- The name of a given file appears in exactly one directory.

- Files can only be added to directories when they are created.

- A file and the directory in which its name is kept must reside on the same device.