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[{$pagename}] ([NACK], [NAK]) [Control character] is sent to reject a previously received [message], or to indicate some kind of [error]. 

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[{ReferringPagesPlugin before='*' after='\n' }]
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* [#1] - [Acknowledgement_(data_networks)|Wikipedia:Acknowledgement_(data_networks)|target='_blank'] - based on information obtained 2018-09-17-