This routine takes the command string specified and passes it to
    the editor. TPU uses the information from this command string
    for initialization purposes, just as though you had entered the
    command at the DCL level.

    Using the simplified callable interface does not set TPU$CLOSE_
    SECTION. This feature lets you make multiple calls to TPU$TPU
    without requiring you to open and close the section file on each
    call.

    If your application parses information that is not related to the
    operation of TPU, make sure the application obtains and uses
    all non-TPU parse information before the application calls
    TPU$TPU. This is because TPU$TPU destroys all parse information
    obtained and stored before TPU$TPU was called.