TM 11-5815-602-10
EE161-DM-OPI-010/E154UGC74
TO 31W4-2UGC74-1
a. General
(CC)Communication Control: A functional character intended to control or facilitate transmis-
sion of information over communication networks.
(FE) Format Effecter: A functional character which controls the layout or positioning of infor-
mation in printing or display devices.
(IS)lnformation Separator: A character which is used to separate and qualify information in a
logical sense. There is a group of four such characters, which are to be used in order of
precedence.
NOTE
On the AN/UGC-74A(V)3, the CTL (Control Key) has no effect on the codes
generated from keys with no control character groups on the keytops. The
two or three character groups shown on the left side of the keytops are
control codes entered when the control key is operated regardless of the
position of the SHIFT key(s).
NUL The transmitted ASCII control character where all code bits are zero. One of the uses of
NUL is to insure acceptance and transmission of the first character of the message header.
The header will be preceded by at least 6 NULS and 6 delete functions (with DEL key).
SOH (Start of Heading): A communication control character used at the beginning of a se-
quence of characters which constitute a machine-sensible address or routing information. Such a
sequence is referred to as the "heading". An STX character has the effect of terminating a
heading.
STX(Start of Text): A communication control character which precedes a sequence of
characters that is to be treated as a complete group and transmitted through to the final destina-
tion. Such a sequence is referred to as "text". STX may be used to terminate a sequence of
characters started by SOH.
ETX(End of Text): A communication control character used to terminate a sequence of
characters started with STX and transmitted as a complete group.
EOT(End of Transmission): A communication control character, used to indicate the conclu-
sion of a transmission, which may have contained one or more texts and any associated
headings.
ENQ(Enquiry): A communication control character used in data communication systems as a
request for a response from a remote station. It may be used as a "Who Are You" (WRU) to obtain
identification, or may be used to obtain station status. or both.
ACK(Acknowledge): A communication control character transmitted by a receiver as an affirm-
ative response to a sender.
E-7
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