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

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).

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(such as "ESC"), or caret notation (such as "^[") are still in use, the graphical symbols of ISO 2047 are considered outdated and rare.[5]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 ⊠[lower-alpha 1] U+22A0 EQ
06 TC6, ACK Acknowledge ✓ U+2713 AK
07 BEL Bell ⍾ U+237E[9] BL
08 FE0, BS Backspace ⤺ —[lower-alpha 2] 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[lower-alpha 3] Device Control 2 ◶ U+25F6 D2
13 DC3, XOF, XOFF Device Control 3 ◵ U+25F5 D3
14 DC4, COF, KMC,[10] TAPE[lower-alpha 3] 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 ▨ —[lower-alpha 4] 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. 1 2 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.

References

  1. 1 2 3 "ISO 2047:1975 Information processing – Graphical representations for the control characters of the 7-bit coded character set". ISO. Retrieved 13 April 2020.
  2. 1 2 "ECMA-17, Graphic Representation of the Control Characters of the ECMA 7-Bit Coded Character Set for Information Interchange". (withdrawn)
  3. ↑ "American National Standard – Graphic Representation of the Control Characters of American National Standard Code for Information Interchange". American National Standards Institute. 3 July 1973.
  4. ↑ "KS X 1010-2007 Graphical representations control characters for Information interchange".
  5. ↑ Agim Çami, "Control characters in ASCII and Unicode" (PDF). Agim Çami – Computer Architecture web site. 1 July 2019.
  6. ↑ Michael P. Frank (14 September 2006). "A Proposed Set of Mnemonic Symbolic Glyphs for the Visual Representation of C0 Controls and Other Nonprintable ASCII Characters" (PDF). (mirror)
  7. ↑ "Information Representation". 28 August 2016. – This is the site cited by Michael P. Frank
  8. ↑ "Information Technology - Irish 7-bit coded character sets". 13 December 1995. – Note that in this article the glyphs for ENQ, BS, CR and SO are anomalous, possibly to accommodate the low resolution.
  9. 1 2 3 4 Specifically cited in The Unicode Standard, Version 6.2. Miscellaneous Technical. Range: 2300–23FF.
  10. 1 2 3 Comité Consultatif International Télégraphique et Téléphonique (31 July 1987). Primary Control Set of Data Syntax II of CCITT Rec. T.101 (PDF). ITSCJ/IPSJ. ISO-IR-134.
    "Terminals for Telematic Services, International Interworking for Videotex Services". International Telecommunication Union. 11 November 1994. A.3.9 General control characters.
  11. ↑ Robert McConnell; James Haynes; Richard Warren (December 2002). "Understanding ASCII Codes". NADCOMM.
  12. ↑ Specifically cited in The Unicode Standard, Version 6.2. Control Pictures. Range: 2400–243F.
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