Unicode (redirected from Unicode 5.0)

Unicode (y`nĭkōd'), set of codes used to represent letters, numbers, control characters, and the like, designed for use internationally in computers. It has been expanded to include such items as scientific, mathematical, and technical symbols, and even musical notation. The Unicode standard defines codes for linguistic symbols used in every major language written today. It includes the Latin alphabet used for English, the Cyrillic alphabet used for Russian, the Greek, Hebrew, and Arabic alphabets, and other alphabets and alphabetlike writing systems used in countries across Europe, Africa, the Indian subcontinent, and Asia, such as Japanese kana, Korean hangeul, and Chinese bopomofo. A large part of the Unicode standard is devoted to thousands of unified character codes for Chinese, Japanese, and Korean ideographs. Adopted as an international standard in 1992, Unicode was originally a "double-byte," or 16-digit, binary number (see numeration) code that could represent up to 65,536 items. No longer limited to 16 bits, it can now represent about one million code positions using three encoding forms called Unicode Transformation Formats (UTF). UTF-8, which consists of one-, two-, three-, and four-byte codes, is used extensively in World Wide Web applications; UTF-16, which consists of two- and four-byte codes, is used primarily for data storage and text processing; and UTF-32, which consists of four-byte codes, is used where character handling must be as efficient as possible. See also ASCII.

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Unicode

International character-encoding system designed to support the electronic interchange, processing, and display of the written texts of the diverse languages of the modern and classical world. The Unicode Worldwide Character Standard includes letters, digits, diacritics, punctuation marks, and technical symbols for all the world's principal written languages, using a uniform encoding scheme. The first version of Unicode was introduced in 1991; the most recent version contains almost 50,000 characters. Numerous encoding systems (including ASCII) predate Unicode. With Unicode (unlike earlier systems), the unique number provided for each character remains the same on any system that supports Unicode.

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Unicode

A character code that defines every character in most of the speaking languages in the world. Although commonly thought to be only a two-byte coding system, Unicode characters can use only one byte, or up to four bytes, to hold a Unicode "code point." The code point is a unique number for a character or some character aspect such as an accent mark or ligature. Unicode supports more than a million code points, which are written with a "U" followed by a plus sign and the number in hex; for example, the word "Hello" is written U+0048 U+0065 U+006C U+006C U+006F (see hex chart).

Character Encoding Schemes
There are several formats for storing Unicode code points. When combined with the byte order of the hardware (big endian or little endian), they are known officially as "character encoding schemes." They are also known by their UTF acronyms, which stand for "Unicode Transformation Format" or "Universal Character Set Transformation Format." See byte order.

UTF-8 is widely used because the first 128 bits in the byte are ASCII, and although up to four bytes can be used, only one byte is required for use in the English speaking world. UTF-16 and UTF-32 use a fixed number of bytes. See DBCS.

   Unicode   ISO         Number
   Coding    10646       of      Byte
   Scheme    Equivalent  Bytes   Order**

   UTF-8                 1-4     BE or LE

   UTF-16    (UCS-2)     2       BE or LE
   UTF-16BE  (UCS-2)     2       BE
   UTF-16LE  (UCS-2)     2       LE

   UTF-32    (UCS-4)     4       BE or LE
   UTF-32BE  (UCS-4)     4       BE
   UTF-32LE  (UCS-4)     4       LE


   Pure ASCII
   (compatible with early 7-bit e-mail systems)

   UTF-7                 1-4     BE or LE


   **Byte Order (see byte order)
     BE = big endian
     LE = little endian

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Unicode

Computing a character set for all languages

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Unicode - 1. A 16-bit character set standard, designed and maintained by the non-profit consortium Unicode Inc. Originally Unicode was designed to be universal, unique, and uniform, i.e., the code was to cover all major modern written languages (universal), each character was to have exactly one encoding (unique), and each character was to be represented by a fixed width in bits (uniform). Parallel to the development of Unicode an ISO/IEC standard was being worked on that put a large emphasis on being compatible with existing character codes such as ASCII or ISO Latin 1. To avoid having two competing 16-bit standards, in 1992 the two teams compromised to define a common character code standard, known both as Unicode and BMP. Since the merger the character codes are the same but the two standards are not identical. The ISO/IEC standard covers only coding while Unicode includes additional specifications that help implementation. Unicode is not a glyph encoding. The same character can be displayed as a variety of glyphs, depending not only on the font and style, but also on the adjacent characters. A sequence of characters can be displayed as a single glyph or a character can be displayed as a sequence of glyphs. Which will be the case, is often font dependent. See also Jürgen Bettels and F. Avery Bishop's paper Unicode: A universal character code.