C0 and C1 control codes

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The C0 and C1 control code sets define control codes for use in text. C0, originally defined in ISO 646, defines codes in the range 00_HEX–1F_HEX. C1, originally defined in ISO 6429, defines codes in the range 80_HEX–9F_HEX. The C0 codes are contained in ASCII and most encodings based on it. The C1 codes were included in the ISO-8859-n series of encodings and Unicode but are rarely used directly, except on specific platforms such as OpenVMS. When they turn up in documents, Web pages, e-mail messages, etc., which are ostensibly in an ISO-8859-n encoding, their code positions generally actually refer to the characters at that position in a proprietary, system-specific encoding such as Windows-1252 or the Apple Macintosh ("MacRoman") character set, though this is technically invalid under the ISO encodings. Such characters are more commonly accessed using the equivalent two octet escape sequence.

Most applications only interpret the C0 control codes for LF, CR, and HT. A few applications also interpret C0 codes VT and FF, and the C1 code NEL. Very few applications interpret the other C0 and C1 control codes.

1 C0 (ASCII and derivatives)
2 C1 (ISO 8859 and Unicode)
3 References

[edit] C0 (ASCII and derivatives)

Seq	Dec	Hex	Abbr	Character name	Description/notes
^@	00	0x00	NUL	Null	Originally used to allow gaps to be left on paper tape for edits. Later used for padding after a code that might take a terminal some time to process (e.g. a carriage return or line feed on a printing terminal). Now often used as a string terminator, especially in the C programming language.
^A	01	0x01	SOH	Start of Heading	First character of a message heading. In some computer terminals, moves cursor to the first column.
^B	02	0x02	STX	Start of Text	First character of message text, and may be used to terminate the message heading.
^C	03	0x03	ETX	End of Text	Often used as a "break" character (Ctrl-C) to interrupt or terminate a program or process. In TOPS-20, it was used to gain the system's attention before logging in.
^D	04	0x04	EOT	End of Transmission	Used on Unix to signal end-of-file condition on, or to logout from, a terminal. On Apple II systems, it signaled that a DOS command followed.
^E	05	0x05	ENQ	Enquiry	Signal intended to trigger a response at the receiving end, to see if it is still present. In some computer terminal and EMACS , moves the cursor to the end of current line.
^F	06	0x06	ACK	Acknowledge	response to an ENQ, or an indication of successful receipt of a message.
^G	07	0x07	BEL	Bell	Originally used to sound a bell on the terminal. Later used for a beep on systems that didn't have a physical bell. May also quickly turn on and off inverse video (a visual bell).
^H	08	0x08	BS	Backspace	Move the cursor one position leftwards. On input, this may delete the character to the left of the cursor.
^I	09	0x09	HT	Horizontal Tab	Position to the next horizontal tab stop.
^J	10	0x0A	LF	Line Feed	On typewriters, printers, and some terminal emulators, moves the cursor down one row without affecting its column position. On Unix, used to mark end-of-line. In MS-DOS, Windows, and various network standards, used following CR as part of the end-of-line mark.
^K	11	0x0B	VT	Vertical Tab	Position the form at the next vertical tab stop.
^L	12	0x0C	FF	Form Feed	On printers, load the next page. Treated as whitespace in many programming languages, and may be used to separate logical divisions in code. In some terminal emulators, it clears the screen.
^M	13	0x0D	CR	Carriage Return	Originally used to move the cursor to column zero while staying on the same line. On Mac OS (pre-Mac OS X), as well as in earlier systems such as the Apple II and Commodore 64, used to mark end-of-line. In MS-DOS, Windows, and various network standards, it is used preceding LF as part of the end-of-line mark. The Enter or Return key on a keyboard will send this character, but it may be converted to a different end-of-line sequence by a terminal program.
^N	14	0x0E	SO	Shift Out	Switch to an alternate character set.
^O	15	0x0F	SI	Shift In	Return to regular character set after Shift Out. In TOPS-20, it signalled that further output should be discarded; the program would continue to run but not display or print anything until ^O is typed again.
^P	16	0x10	DLE	Data Link Escape	Cause the following data to be interpreted as raw data, not control codes.
^Q	17	0x11	DC1	Device Control 1/XON	Resume transmission. Used for software flow control. In some terminal programs, ends pause started with Ctrl-S.
^R	18	0x12	DC2	Device Control 2	In TOPS-20, reprinted the current line, tidying up any character deletions.
^S	19	0x13	DC3	Device Control 3/XOFF	Suspend transmission. Used for software flow control. In some terminal programs, pauses display of text.
^T	20	0x14	DC4	Device Control 4	In TOPS-20, it caused a brief system-status line to be displayed.
^U	21	0x15	NAK	Negative Acknowledge	Sent by a station as a negative response to the station with which the connection has been set up. In binary synchronous communication protocol, the NAK is used to indicate that an error was detected in the previously received block and that the receiver is ready to accept retransmission of that block. In multipoint systems, the NAK is used as the not-ready reply to a poll. In some text editors, it was used as a "Delete Line" character.
^V	22	0x16	SYN	Synchronous Idle	Used in synchronous transmission systems to provide a signal from which synchronous correction may be achieved between data terminal equipment, particularly when no other character is being transmitted. In some terminal programs, allows literal entry of control codes without them being interpreted.
^W	23	0x17	ETB	End of Transmission Block	Indicates the end of a transmission block of data when data are divided into such blocks for transmission purposes. In some text editors, it is used as a "Delete Word" character which rubs out the previous text entry back to the preceding space.
^X	24	0x18	CAN	Cancel	Indicates that the data with which it is associated are in error or are to be disregarded, or cannot be represented on a particular device.
^Y	25	0x19	EM	End of Medium	In many programs, a keyboard input of Ctrl-Y is a "redo" command to undo the last Ctrl-Z undo command.
^Z	26	0x1A	SUB	Substitute	On MS-DOS systems with files opened in text mode, "end of text" or "end of file" is marked by the Ctrl-Z character (code 26, "Substitute"), instead of ^C or ^D common on other operating systems. In many programs, a keyboard input of Ctrl-Z is an "undo" command to reverse the most recent input or action. In many terminal programs, this will suspend the active process and return control to the shell.
^[	27	0x1B	ESC	Escape	The ESC key on the keyboard will cause this character to be sent on most systems. It can be used in software user interfaces to exit from a screen, menu, or mode, or in device-control protocols (e.g., printers and terminals) to signal that what follows is a special command sequence rather than normal text.
^\	28	0x1C	FS	File Separator	Can be used as delimiters to mark fields of data structures. If used for hierarchical levels, US is the lowest level (dividing plain-text data items), while RS, GS, and FS are of increasing level to divide groups made up of items of the level beneath it. These can usually be generated by holding down Ctrl and the backslash, right square bracket, caret, and underscore keys respectively.
^]	29	0x1D	GS	Group Separator
^^	30	0x1E	RS	Record Separator
^_	31	0x1F	US	Unit Separator
^?	127	0x7F	DEL	Rubout/Delete	Originally used to mark deleted characters on paper tape, since any character could be changed to all ones by punching holes everywhere. On VT100 compatible terminals, this is the character generated by the key labelled ⌫, usually called backspace on modern machines, and does not correspond to the PC delete key.

[edit] C1 (ISO 8859 and Unicode)

Dec	Hex	Esc Seq	Short Abbr (RFC 1345)	Full Abbr	Character name	Description/notes
128	0x80	0x1B 0x40	PA	PAD	Padding Character	listed as XXX in unicode
129	0x81	0x1B 0x41	HO	HOP	High Octet Preset	listed as XXX in unicode
130	0x82	0x1B 0x42	BH	BPH	Break Permitted Here
131	0x83	0x1B 0x43	NH	NBH	No Break Here
132	0x84	0x1B 0x44	IN	IND	Index	Deprecated in 1986 and withdrawn in 1991 from ISO/IEC 6429 (ECMA-48)
133	0x85	0x1B 0x45	NL	NEL	Next Line	Used to mark end-of-line on some IBM mainframes.
134	0x86	0x1B 0x46	SA	SSA	Start of Selected Area
135	0x87	0x1B 0x47	ES	ESA	End of Selected Area
136	0x88	0x1B 0x48	HS	HTS	Horizontal Tab Set
137	0x89	0x1B 0x49	HJ	HTJ	Horizontal Tab Justified
138	0x8A	0x1B 0x4A	VS	VTS	Vertical Tab Set
139	0x8B	0x1B 0x4B	PD	PLD	Partial Line Forward	Used to produce subscripts and superscripts in ISO/IEC 6429, e.g., in a printer. Subscripts use `PLD text PLU` while superscripts use `PLU text PLD.`.
140	0x8C	0x1B 0x4C	PU	PLU	Partial Line Backward
141	0x8D	0x1B 0x4D	RI	RI	Reverse Line Feed
142	0x8E	0x1B 0x4E	S2	SS2	Single-Shift 2
143	0x8F	0x1B 0x4F	S3	SS3	Single-Shift 3
144	0x90	0x1B 0x50	DC	DCS	Device Control String
145	0x91	0x1B 0x51	P1	PU1	Private Use 1
146	0x92	0x1B 0x52	P2	PU2	Private Use 2
147	0x93	0x1B 0x53	TS	STS	Set Transmit State
148	0x94	0x1B 0x54	CC	CCH	Cancel character
149	0x95	0x1B 0x55	MW	MW	Message Waiting
150	0x96	0x1B 0x56	SG	SPA	Start of Protected Area
151	0x97	0x1B 0x57	EG	EPA	End of Protected Area
152	0x98	0x1B 0x58	SS	SOS	Start of String
153	0x99	0x1B 0x59	GC	SGCI	Single Graphic Char Intro	listed as XXX in unicode
154	0x9A	0x1B 0x5A	SC	SCI	Single Char Intro
155	0x9B	0x1B 0x5B	CI	CSI	Control Sequence Introducer
156	0x9C	0x1B 0x5C	SI	ST	String Terminator
157	0x9D	0x1B 0x5D	OC	OSC	OS Command
158	0x9E	0x1B 0x5E	PM	PM	Private Message
159	0x9F	0x1B 0x5F	AC	APC	App Program Command