The device driver can be told to transmit a byte immediately, bypassing the normal file system Write requests (bypassing the data to be transmitted in the transmit queue). Only one character at a time can be waiting to be transmitted immediately.

Initial Value

There is no character waiting to be transmitted immediately.
First Level Open
There is no character waiting to be transmitted immediately.
Close Considerations
A CLOSE request packet, when after processing this close request the port is not open any more (from another open without a close), causes the device driver to attempt to transmit the character waiting to be transmitted immediately. If the physical device driver cannot transmit the character waiting to be transmitted immediately (see IOCtl ASYNC_TRANSMITIMM), it does not try to transmit the character and proceeds with the close processing.
Mode Utility
Not applicable.

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