Signals are different in that they cannot return anything: there is neither a "signal return" message, nor any other type of error message.
信号的不同之处在于它们不返回任何内容：既没有“信号返回”消息，也没有任何类型的错误消息。
A Label control to signal whether the message was sent or an error was encountered.
Label控件用于通知消息被发送还是遇到错误。
Signal unit error detection and correction - discards detected erroneous message and requests a re-transmission.
信令单元错误检测和校正——废弃检测到的出错消息并请求重新传输。
Signal unit error detection and correction - discards detected erroneous message and requests a re-transmission.
信令单元错误检测和校正——废弃检测到的出错消息并请求重新传输。
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