supervisory message

A short message relating to operation of the data link on which it is sent. It is, typically, a single character (say, ACK or NAK) plus those characters required for error detection. It may be sent as an ordinary return message in either a full duplex or halfduplex system; in an asymmetric duplex system, it is sent on the “supervisory channel”.; 在數據鏈路上傳送的與數據鏈路操作關聯的一種簡短信息。這種信息一般是一單個字符(如ACK或NAK)加上那些錯誤檢查所需要的字 符。在全雙工或半雙工系統中,這種信息可以作為一種普通返回信息傳送;在非對稱雙工系統 中,這種信息在“管理信道”上傳送。