The TPU$CLOSE_TERMINAL routine closes the TPU channel to the
    terminal.

    Format

      TPU$CLOSE_TERMINAL

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

    Longword condition value. Most utility routines return a
    condition value in R0. The condition value that this routine
    can return is listed under Condition Value Returned.

2  –  Arguments

    None.

3  –  Description

    This routine is used with the built-in procedure CALL_USER and
    its associated call-user routine to control the TPU access
    to the terminal. When a call-user routine invokes TPU$CLOSE_
    TERMINAL, TPU closes its channel to the terminal and the
    channel of the TPU associated mailbox.

    When the call-user routine returns control to it, TPU
    automatically reopens a channel to the terminal and redisplays
    the visible windows.

    A call-user routine can use TPU$CLOSE_TERMINAL at any point in
    the program and as many times as necessary. If the terminal is
    already closed to TPU when TPU$CLOSE_TERMINAL is used, the
    call is ignored.

4  –  Condition Value Returned

    TPU$_SUCCESS       Normal successful completion.