Purging Data to End of Chain
When the host sends a chain of request units to an LUA application, the application may wait until the last RU in the chain is received before sending a response, or it may send a negative response to an RU which is not the last in the chain. If a negative response is sent mid-chain, Personal Communications purge all subsequent RUs from this chain, and do not send them to the application.
When Personal Communications receive the last RU in the chain, it indicates this to the application
by setting the primary return code of an RUI_READ or RUI_BID verb to LUA_NEGATIVE_RSP with a zero secondary return
code.
Note: The host may terminate the chain by sending a message
such as CANCEL while in mid-chain. In this case, the CANCEL message is returned
to the application on an RUI_READ verb, and the LUA_NEGATIVE_RSP
return code is not used.