VMS Help LSEDIT, Command Qualifiers, /READ_ONLY  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  /READ_ONLY
  /NOREAD_ONLY

  Specifies that LSE will create an unmodifiable,  read_only  buffer  for
  the  input  file.   LSE will not create a new output file for the input
  file.  Any changes to the file will be lost  upon  exiting.   If  other
  buffers  were  modified during the editing session, this qualifier will
  not affect their being written back to their associated files.