RedGrittyBrick

Some Common Character-Sets

Here is a comparison of some character sets that are, or have been, commonly used in English speaking countries such as the USA and UK.

They can be grouped into three categories: 7-bit character sets like ASCII with numeric-values / code-points running from 0 to 127; 8-bit character sets like “Windows Latin–1” and “ISO 8859–1 Latin–1” which have numeric-values / code-points from 0 to 256; Multi-byte character sets such as the Unicode character set.

Note that Unicode has numeric values / code-points running from 0 up into the millions. 32-bits is insufficient to represent all Unicode characters. Typically Unicode is encoded in UTF–8 which uses a variable number of bytes to represent each character. The tables below only show the first 256 characters.

Key

Characters

Notes

• The PC ROM had displayable glyphs at code-points 0 through 31, as did some printers.
• ASCII is a 7-bit character set.
• Windows Latin 1 is not ISO Latin 1, compare code points 128 through 159.
• Code Page 850 differs from 437 at places such as code point 181 where accented characters replace line-draw characters.

Glossary of Control Characters

There are a large number of control characters which originally were used to organise transmission of data and to provide control over the movement of parts in mechanical printers. Few of these are still used for their original purpose.

NUL

Padding character.

SOH

Start of Header.

STX

Start of Text. See ETX.

ETX

End of Text. See STX. Also known as Ctrl+C and used to interrupt a program.

EOT

End of Transmission. Also known as Ctrl+D and used to signal end of file or end of data.

ENQ

Enquiry. See ACK, NAK.

ACK

Acknowledgement. See Enq, NAK.

BEL

Audible signal. Also known as Ctrl+G

BS

Backspace. Moves print position one place left. originally used on printers for overprinting one character on top of another. E.g. “O BS /” makes Ø. BS is also known as Ctrl+H

HT

Horizontal Tab. Advances print position rightwards, typically to the next column-position that is a multiple of 8 character-widths.

LF

Line Feed. Advances print position down one line. See CR.

VT

Vertical Tab.

FF

Form Feed. Advance print position to top of next sheet/page.

CR

Carriage Return. Move print position back to left margin.

SO

Shift Out. Switches to an alternate character set, often one used for graphics characters rather than for alphabetic characters. See SI.

SI

Shift In. Returns to normal character set. See SO.

DL

Data Link Escape. Following octets are data, not characters.

DC1

Device Control 1. Also known as X-On. Resume operation. See DC3/X-Off.

DC2

Device Control 2.

DC3

Device Control 3. Also known as X-off. Suspend operation. used for communications flow control, tells other end to temporarily stop sending data until this end has caught up. See DC1/X-on.

DC4

Device Control 4.

NAK

Negative Acknowledgement. Not ready or error in prior block. See ENQ, ACK.

SYN

Synchronous Idle. Used in synchronous transmission.

ETB

End of Transmission Block.

CAN

Cancel. Previously sent data is erroneous and should be discarded.

EM

End of Medium. For example, end of paper tape.

SUB

Substitute. Used to mark end of useful data in last block where a fixed-sized block is used. Sometimes used as a filler for unused space in a block. Also Ctrl+Z used to signal a program to suspend execution.

ESC

Escape. Often used as the start of an “Escape Sequence”. See CSI.

FS

Field Separator. One of the hierarchical data separators. See GS, RS, US.

GS

Group Separator. One of the hierarchical data separators. See FS, RS, US.

RS

Record separator. One of the hierarchical data separators. See FS, GS, US.

US

Unit Separator. One of the hierarchical data separators. See FS, GS, RS.

XXX

Unused?

BPH

Break Permitted Here. Indicates that a line-break is allowed here.

NBH

No Break Here. Follows a character that is not to be separated by a line-break from the following character.

IND

Deprecated, moves active position down one line. Compare LF.

NEL

Next Line. Compare CR,LF.

SSA

Start of Selected Area. See ESA.

ESA

End of Selected Area. See SSA.

CTS

Character Tabulation Set. Sets a tab-position at current location. See TAB.

HTJ

Horizontal Tabulation with Justification. Moves preceding text (from prior tab position) to right-align with next tab position.

VTS

Line Tabulation Set. Sets a vertical tabulation stop at current position. See VT.

PLD

Partial Line Down/forward. Used for subscripts or to end PLU.

PLU

Partial Line Up/backward. Used for superscripts or to end PLD.

RI

Reverse Line Feed. See LF. Moves to prior line, same horizontal position.

SS2

Single Shift Two. Switch to character set G2.

SS3

Single Shift Three. Switch to character set G3.

DCS

Device Control String. Ended by ST. Used to send commands or a status report.

PU1

Private Use One.

PU2

Private Use Two.

STS

Set Transmit State. Indicates that data is available for transmission.

CCH

Cancel Character. Ignore previous character. Destructive backspace. See BS.

MW

Message Waiting.

SPA

Start of Guarded Area. Following characters not to be altered, transmitted or (optionally) erased. See EPA.

EPA

End of Guarded Area. See SPA.

SOS

Start of String.

SCI

Single Character Introducer. Purpose not fully defined.

CSI

Control Sequence Introducer. Used to indicate the start of a group of characters that are not to be printed or displayed but which are to be used to move the cursor, change colours or perform some other change to the display state. See Esc.

ST

String Terminator. See APC, DCS, OSC, PM, SOS.

OSC

Operating System Command.

PM

Privacy Message.

APC

Application Program Command.

NBSP

No-Break Space. Used to join two words that should not be split across the end of a line.

SHY

Soft Hyphen. Indicates where a word can be broken across a line with a hyphen used to indicate the break.

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