A directory file is a file containing a listing of a directory in Files-11 directory structure. It always has the extension of .DIR and version 1. With the exception of 000000.DIR;1, directory files are located in the parent directory. Directory files are created automatically when a directory is created with the CREATE/DIRECTORY command.
To check whether a file is a directory file, use F$FILE_ATTRIBUTES(filename,"DIRECTORY") - this returns true if filename is a directory file.
UIC protection of directory files
Read access to a directory file gives you the right to read or list a file and use a filename with characters to look up files. Write access to directory files gives you the right to insert or delete an entry in the catalog of files - which means creating and deleting files. Execute access to a directory files gives you the right to look up files whose names you know. Delete access to a directory file gives you the right to delete that file.
Overriding default UIC protection
A default protection ACE can be placed in the ACL of a directory file to specify the default protection that will be applied to any new file created in this directory or subdirectory of this directory.
$ SET SECURITY/ACL = (DEFAULT_PROTECTION,S:RWED,O:RWED,G:RE,W:) [JONES]PERSONAL.DIR