NAME
        CloseDevice -- conclude access to a device

   SYNOPSIS
        CloseDevice(iORequest)
                    A1

        void CloseDevice(struct iorequest *);

   FUNCTION
        This function informs the device that access to a device/unit
        previously opened has been concluded.  The device may perform
        certain house-cleaning operations.

        The user must ensure that all outstanding IORequests have been
        returned before closing the device.  The abortio function can kill
        any stragglers.

        After a close, the I/O request structure is free to be reused.
        Starting with V36 exec it is safe to CloseDevice() with an
        iorequest that is either cleared to zeros, or failed to
        open.

   INPUTS
        iORequest - pointer to an I/O request structure

   SEE ALSO
        opendevice()