/sys$common/syshlp/helplib.hlb LSEDIT, Parameter  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       file-spec

         specifies  the  file to be edited (use only OpenVMS file
          specifications).

          If no file specification is entered, LSE defaults
          to the last file edited by an LSEDIT command.

  If the file exists, LSE reads the file into the main  buffer;  and  the
  main  buffer  takes  for  its  name  the  name  and  type  of  the file
  specification on the  command  line.   The  file  type  determines  the
  default  language  that  will be used.  (For example, .FOR for FORTRAN,
  .PLI for PL/I, or .PAS for PASCAL.)

  If the specified file exists, it is  opened.   If  the  file  does  not
  exist,  it  is created when you leave LSE with an EXIT command.  If you
  leave LSE with  a  QUIT  command  a  file  will  not  be  created  and,
  therefore, a specified file will not be saved.