Syntax:  SET DIRECTORY READONLY directory_spec add_remove

  Sets the indicated directory's read/write state.

  This command adds the directory or removes it from the list of read
  only directories.

  LSE does not look at a directory's file-system protection to
  determine whether or not it should be set to read- only.  As such, if
  a file is read from a directory that is write-protected by the file
  system, it is not set to read-only.  If you modify the buffer, LSE
  will attempt to write the file out and you will get an error message
  from the operating system.