ISO 2047

ISO 2047 (Information processing – Graphical representations for the control characters of the 7-bit coded character set) is a standard for graphical representation of the control characters for debugging purposes, such as may be found in the character generator of a computer terminal; it also establishes a two-letter abbreviation of each control character.^[1] The graphics and two-letter codes are essentially unchanged from the 1968 European standard ECMA-17^[2] and the 1973 American standard ANSI X3.32-1973.^[3] It became an ISO standard in 1975.^[1] It is also standardized as GB/T 3911-1983 in China, as KS X 1010^[4] in Korea (formerly KS C 5713), and was enacted in Japan as "graphical representation of information exchange capabilities for character" JIS X 0209:1976 (former JIS C 6227) (abolished January 20, 2010).

Early symbols assigned to the 32 control characters, space and delete characters. (ISO 2047, MIL-STD-188-100, 1972)

While the ISO/IEC 646 three-letter abbreviations (such as "ESC"), or caret notation (such as "^[") are still in use, the graphical symbols of ISO 2047 are considered outdated and rare.^[5]

Character table

Code (hex)	Common abbreviation	Name	Symbol[1][2][6][7][8]		2-letter abbreviation
00	NUL	Null	⎕	U+2395	NU
01	TC1, SOH	Start of Heading	⌈	U+2308	SH
02	TC2, STX	Start of Text	⊥	U+22A5	SX
03	TC3, ETX	End of Text	⌋	U+230B	EX
04	TC4, EOT	End of Transmission	⌁	U+2301[9]	ET
05	TC5, ENQ	Enquiry	⊠[a]	U+22A0	EQ
06	TC6, ACK	Acknowledge	✓	U+2713	AK
07	BEL	Bell	⍾	U+237E[9]	BL
08	FE0, BS	Backspace	⤺	—[b]	BS
09	FE1, HT	Horizontal Tabulation	⪫	U+2AAB	HT
0A	FE2, LF	Line Feed	≡	U+2261	LF
0B	FE3, VT	Vertical Tabulation	⩛	U+2A5B	VT
0C	FE4, FF	Form Feed	↡	U+21A1	FF
0D	FE5, CR	Carriage Return	⪪	U+2AAA	CR
0E	SO	Shift Out	⊗	U+2297	SO
0F	SI	Shift In	⊙	U+2299	SI
10	TC7, DLE	Data Link Escape	⊟	U+229F	DL
11	DC1, XON, CON[10]	Device Control 1	◷	U+25F7	D1
12	DC2, RPT,[10] TAPE[c]	Device Control 2	◶	U+25F6	D2
13	DC3, XOF, XOFF	Device Control 3	◵	U+25F5	D3
14	DC4, COF, KMC,[10] TAPE[c]	Device Control 4	◴	U+25F4	D4
15	TC8, NAK	Negative Acknowledge	⍻	U+237B[9]	NK
16	TC9, SYN	Synchronization	⎍	U+238D	SY
17	TC10, ETB	End of Transmission Block	⊣	U+22A3	EB
18	CAN	Cancel	⧖	U+29D6	CN
19	EM	End of Medium	⍿	U+237F[9]	EM
1A	SUB	Substitute Character	␦	U+2426[12]	SB
1B	ESC	Escape	⊖	U+2296	EC
1C	IS4, FS	File Separator	◰	U+25F0	FS
1D	IS3, GS	Group Separator	◱	U+25F1	GS
1E	IS2, RS	Record Separator	◲	U+25F2	RS
1F	IS1 US	Unit Separator	◳	U+25F3	US
20	SP	Space	△	U+25B3	SP
7F	DEL	Delete	▨	—[d]	DT

Notes

1. In ISO 2047, ✠ is the primary glyph and ⊠ is only a fallback, but ECMA-17 lists only ⊠.
2. As a best-fit approximation ↖ could be used. Other defensible choices could be ⤺, ↰, ⮢, ⮪, ⮌ or ⮏.
3. On the Teletype Model 33 TAPE and TAPE would control the tape punch, whereas XON and XOFF would control the reader. ENQ was labelled WRU for 'who are you?'^[11]
4. As a best-fit approximation ▨, 🮙 or ␥ could be used.