VMS Help CC, /DIAGNOSTICS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

     /DIAGNOSTICS[=file-spec]
     /NODIAGNOSTICS (D)

  Creates a file containing compiler diagnostic messages.  The
  default file extension for a diagnostics file is .DIA.  The
  diagnostics file is used with the DEC Language-Sensitive Editor
  (LSE).  To display a diagnostics file, enter the command
  REVIEW/FILE=file-spec while in LSE.