Editing Stratus VOS (section)

===File system security===
VOS supports write, read, execute, and null (no) access to all files, directories and devices (although directories and files have slightly different access lists). Access can be assigned to users, groups, or the world. Only read access is required to run an executable program, provided that the user has "status" access for the directory in which that program resides.

VOS inherited access control lists from [[Multics]] and also implements directory access control lists. If a file does not have an access control list, the containing directory's default access control list applies.

Access to devices is typically controlled by creating a file which is linked to the device by the administrator. (This may be true in OpenVOS, but does not apply to the original operating system.) Access is then given to this file, and this sets the access on the device.