Binary integer with
the size of the physical device driver receive queue. Applications should
be independent of the receive queue being sized (fixed or not fixed). The
information in this field allows the application to get the size of the
receive queue. The current size of the receive queue is approximately 1KB,
but is subject to change.
Using this information, the application should avoid device driver receive
queue overruns by using an application-to-application block protocol with
the system communicating with the application.