000  $anz n  2
000  $a주제어
001  $aKSH1998000403
005  $a20190618095150
008  $a980429 n azknnaabn          |a a|a    | 
150  $aCCITT 엑스-21 프로토콜[CCITT X-21 protocol]
450  $wr$i영어$aCCITT X-21 protocol
550  $wg$a프로토콜(통신)[protocol]