Ellipsis - Computer Representations

Computer Representations

In computing, several ellipsis characters have been codified, depending on the system used.

In the Unicode standard, there are the following characters:

In Windows, it can be inserted with Alt+0133.

In MacOS, it can be inserted with ⌥ Opt+; (on an English language keyboard).

In Linux, it can be inserted with AltGr+.

In Chinese and sometimes in Japanese, ellipsis characters are done by entering two consecutive horizontal ellipsis (U+2026). In vertical texts, the application should rotate the symbol accordingly.

Unicode recognizes a series of three period characters (U+002E) as compatibility equivalent (though not canonical) to the horizontal ellipsis character.

In HTML, the horizontal ellipsis character may be represented by the entity reference … (since HTML 4.0), and the vertical ellipsis character by the entity reference ⋮ (since HTML 5.0). Alternatively, in HTML, XML, and SGML, a numeric character reference such as … or … can be used.

In the TeX typesetting system, the following types of ellipsis are available:

The horizontal ellipsis character also appears in the following older character maps:

• in Windows-1250—Windows-1258 and in IBM/MS-DOS Code page 874, at code 85 (hexadecimal)
• in Mac-Roman, Mac-CentEuro and several other Macintosh encodings, at code C9 (hexadecimal)
• in Ventura International encoding at code C1 (hexadecimal)

Note that ISO/IEC 8859 encoding series provides no code point for ellipsis.

As with all characters, especially those outside of the ASCII range, the author, sender and receiver of an encoded ellipsis must be in agreement upon what bytes are being used to represent the character. Naive text processing software may improperly assume that a particular encoding is being used, resulting in mojibake.

The Chicago Style Q&A recommends to avoid the use of … (U+2026) character in manuscripts and to place three periods plus two nonbreaking spaces (. . .) instead, so that an editor, publisher, or designer can replace them later.

In Abstract Syntax Notation One (ASN.1), the ellipsis is used as an extension marker to indicate the possibility of type extensions in future revisions of a protocol specification. In a type constraint expression like A ::= INTEGER (0..127, ..., 256..511) an ellipsis is used to separate the extension root from extension additions. The definition of type A in version 1 system of the form A ::= INTEGER (0..127, ...) and the definition of type A in version 2 system of the form A ::= INTEGER (0..127, ..., 256..511) constitute an extension series of the same type A in different versions of the same specification. The ellipsis can also be used in compound type definitions to separate the set of fields belonging to the extension root from the set of fields constituting extension additions. Here is an example: B ::= SEQUENCE { a INTEGER, b INTEGER, ..., c INTEGER }