Syntax:  SPAWN cli_command

  Creates a subprocess running a command interpreter and suspends the
  editing session.

  This command suspends the current LSE session and connects your
  terminal to a new process at the command level.

  If you specified a command to execute, the command will be executed
  at the command line interpretter and you will immediately return to
  LSE.  If you don't specify a command, LSE will remain at the command
  level until you terminate the process.  This command is useful for
  running screen- oriented programs and utilities without ending the
  current editing session.