Number of Characters Queued

Binary integer with the number of characters ready to be transmitted in the physical device driver transmit queue. This is a memory buffer between the memory pointed to by the WRITE request packet and the transmit hardware for this COM device. If the transmit queue is empty, the application cannot assume that all Write requests have completed or that no Write requests are outstanding.

Note: The behavior of data movement between the Write request and the transmit queue can change with each release of the physical device driver. Applications should not be dependent on this information.