With DECC$FILE_PERMISSION_UNIX enabled, the file permissions
    for new files and directories are set according to the file
    creation mode and umask. This includes mode 0777. When an earlier
    version of the file exists, the file permissions for the new file
    are inherited from the earlier version. This mode sets DELETE
    permission for a new directory when WRITE permission is enabled.

    With DECC$FILE_PERMISSION_UNIX disabled, modes 0 and 0777
    indicate using RMS default protection or protection from the
    previous version of the file. Permissions for new directories
    also follow OpenVMS rules, including disabling DELETE
    permissions.