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Steuerzeichen
Die ASCII-Zeichen 0 - 31 und das Zeichen 127 werden als Steuerzeichen
bezeichnet. Die meisten dieser Zeichen werden heutzutags nicht mehr
benutzt, einige davon sind jedoch nach wie vor bei bei der Arbeit mit
einem Terminal oder in der Programmierung von grosser Wichtigkeit. In
der folgenden Tabelle sind einige heutzutags wichtigen Anwendungen
aufgelistet:
+----------+----+----------+---------------------------+-------------+
| | | | | |
| 0x00/ 0 | ^@ | NUL | null character | C: \0 |
| 0x01/ 1 | ^A | SOH | start of header | |
| 0x02/ 2 | ^B | STX | start of text | |
| 0x03/ 3 | ^C | ETX | end of text | Abort |
| 0x04/ 4 | ^D | EOT | end of transmission | |
| 0x05/ 5 | ^E | ENQ | enquiry | |
| 0x06/ 6 | ^F | ACK | acknowledge | |
| 0x07/ 7 | ^G | BEL | bell | Beep |
| 0x08/ 8 | ^H | BS | backspace | C: \b |
| 0x09/ 9 | ^I | HT | horizontal tabulation | C: \t |
| 0x0a/ 10 | ^J | LF | line feed | C: \n |
| 0x0b/ 11 | ^K | VT | vertical tabulation | C: \v |
| 0x0c/ 12 | ^L | FF | form feed | C: \f |
| 0x0d/ 13 | ^M | CR | carriage return | C: \r |
| 0x0e/ 14 | ^N | SO | shift out | |
| 0x0f/ 15 | ^O | SI | shift in | |
| 0x10/ 16 | ^P | DLE | data link escape | |
| 0x11/ 17 | ^Q | DC1/XON | device control #1 | Start Trans |
| 0x12/ 18 | ^R | DC2 | device control #2 | rev-i-serch |
| 0x13/ 19 | ^S | DC3/XOFF | device control #3 | Stop Trans |
| 0x14/ 20 | ^T | DC4 | device control #4 | |
| 0x15/ 21 | ^U | NAK | negative acknowledgement | Delete Line |
| 0x16/ 22 | ^V | SYN | synchronous idle | |
| 0x17/ 23 | ^W | ETB | end of transmission block | Delete Word |
| 0x18/ 24 | ^X | CAN | cancel | |
| 0x19/ 25 | ^Y | EM | end of medium | |
| 0x1a/ 26 | ^Z | SUB | substitute | Suspend |
| 0x1b/ 27 | ^[ | ESC | escape | (C: \e) |
| 0x1c/ 28 | ^\ | FS | file separator | |
| 0x1d/ 29 | ^] | GS | group separator | |
| 0x1e/ 30 | ^^ | RS | record separator | |
| 0x1f/ 31 | ^_ | US | unit separator | |
| | | | | |
| 0x7f/127 | ^? | DEL | delete | |
| | | | | |
+----------+----+----------+---------------------------+-------------+
Tabulatoren (Zeichen 9), sowie Zeilenumbrueche (Newlines = NL) treten
auch haeufig in Textdateien auf. Ein Zeilenumbruch wird dabei je nach
System anders codiert:
+-----------------+ +-------------------------+ +----------------+
| Unix: LF \n | | Windows: CR+LF \r\n | | Mac: CR \r |
+-----------------+ +-------------------------+ +----------------+
In Unicode wurden zu diesen Steuerzeichen separate Symbole definiert.
Sie haben keine spezielle Bedeutung. Auch fuer Space (Zeichen 32) und
Newline wurden entsprechende Symbole definiert.
+------------------------+---+---------------------------------------+
| Hex / Dec / UTF-8 | | Unicode Name |
| | | |
| 0x2400 / 9216 / e29080 | ␀ | SYMBOL FOR NULL |
| 0x2401 / 9217 / e29081 | ␁ | SYMBOL FOR START OF HEADING |
| 0x2402 / 9218 / e29082 | ␂ | SYMBOL FOR START OF TEXT |
| 0x2403 / 9219 / e29083 | ␃ | SYMBOL FOR END OF TEXT |
| 0x2404 / 9220 / e29084 | ␄ | SYMBOL FOR END OF TRANSMISSION |
| 0x2405 / 9221 / e29085 | ␅ | SYMBOL FOR ENQUIRY |
| 0x2406 / 9222 / e29086 | ␆ | SYMBOL FOR ACKNOWLEDGE |
| 0x2407 / 9223 / e29087 | ␇ | SYMBOL FOR BELL |
| 0x2408 / 9224 / e29088 | ␈ | SYMBOL FOR BACKSPACE |
| 0x2409 / 9225 / e29089 | ␉ | SYMBOL FOR HORIZONTAL TABULATION |
| 0x240a / 9226 / e2908a | ␊ | SYMBOL FOR LINE FEED |
| 0x240b / 9227 / e2908b | ␋ | SYMBOL FOR VERTICAL TABULATION |
| 0x240c / 9228 / e2908c | ␌ | SYMBOL FOR FORM FEED |
| 0x240d / 9229 / e2908d | ␍ | SYMBOL FOR CARRIAGE RETURN |
| 0x240e / 9230 / e2908e | ␎ | SYMBOL FOR SHIFT OUT |
| 0x240f / 9231 / e2908f | ␏ | SYMBOL FOR SHIFT IN |
| 0x2410 / 9232 / e29090 | ␐ | SYMBOL FOR DATA LINK ESCAPE |
| 0x2411 / 9233 / e29091 | ␑ | SYMBOL FOR DEVICE CONTROL ONE |
| 0x2412 / 9234 / e29092 | ␒ | SYMBOL FOR DEVICE CONTROL TWO |
| 0x2413 / 9235 / e29093 | ␓ | SYMBOL FOR DEVICE CONTROL THREE |
| 0x2414 / 9236 / e29094 | ␔ | SYMBOL FOR DEVICE CONTROL FOUR |
| 0x2415 / 9237 / e29095 | ␕ | SYMBOL FOR NEGATIVE ACKNOWLEDGE |
| 0x2416 / 9238 / e29096 | ␖ | SYMBOL FOR SYNCHRONOUS IDLE |
| 0x2417 / 9239 / e29097 | ␗ | SYMBOL FOR END OF TRANSMISSION BLOCK |
| 0x2418 / 9240 / e29098 | ␘ | SYMBOL FOR CANCEL |
| 0x2419 / 9241 / e29099 | ␙ | SYMBOL FOR END OF MEDIUM |
| 0x241a / 9242 / e2909a | ␚ | SYMBOL FOR SUBSTITUTE |
| 0x241b / 9243 / e2909b | ␛ | SYMBOL FOR ESCAPE |
| 0x241c / 9244 / e2909c | ␜ | SYMBOL FOR FILE SEPARATOR |
| 0x241d / 9245 / e2909d | ␝ | SYMBOL FOR GROUP SEPARATOR |
| 0x241e / 9246 / e2909e | ␞ | SYMBOL FOR RECORD SEPARATOR |
| 0x241f / 9247 / e2909f | ␟ | SYMBOL FOR UNIT SEPARATOR |
| | | |
| 0x2421 / 9249 / e290a1 | ␡ | SYMBOL FOR DELETE |
| | | |
| 0x2420 / 9248 / e290a3 | ␠ | SYMBOL FOR SPACE |
| 0x2424 / 9252 / e290a4 |  | SYMBOL FOR NEWLINE |
| | | |
+------------------------+---+---------------------------------------+
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(c) Tobias Stamm, manderby.com