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

  /SYSTEM_ENVIRONMENT=file-spec
  /SYSTEM_ENVIRONMENT=LSE$SYSTEM_ENVIRONMENT
  /NOSYSTEM_ENVIRONMENT (D)

  Specifies the name  of  a  system  environment  file.   The  difference
  between  files  specified  by  this  qualifier and those specified by a
  /ENVIRONMENT qualifier is:  Definitions  derived  from  this  qualifier
  cannot be saved by a SAVE ENVIRONMENT command.

  The default device is SYS$LIBRARY:  and the default type is .ENV.