Client-Library must read from the result stream in order to discard results, and it is not always safe to read from the result stream. CS_CANCEL_ATTN causes Client-Library to wait until the application attempts to read from the server before discarding the results.
Use CS_CANCEL_ATTN from within callbacks or interrupt handlers. In an asynchronous-mode application, use CS_CANCEL_ATTN when completion of an asynchronous call is pending.
