Extended ASCII has 2 8 = 256 code points. For example, the ASCII code space consists of 2 7 = 128 code points and each of the represented characters corresponds to a code point and to a predefined bit sequence. Some character encoding schemes, such as ASCII, have a fixed relationship between any of the represented characters and the sequence of bits used to represent that character. Code PointĪ code point, or a code position, is any of the integral numeric values that make up the code space. Unicode is sometimes referred to as a character code. Character encoding schemes include UTF-8, UTF-16 and UTF-32. This correspondence is defined by a CEF.Ī character encoding scheme (CES) is the mapping of code units to a sequence of bits to facilitate storage on an octet-based file system or transmission over an octet-based network. For example, a system that stores numeric information in 16-bit units can only directly represent code points 0 to 65,535 in each unit, but larger code points (for example, 65,536 to 1.4 million) could be represented by using multiple 16-bit units. A character set might be used by multiple languages.Ī character encoding form (CEF) is the mapping of code points to code units to facilitate storage or transmission in a system that represents numbers as bit sequences of fixed length. "Coded character set" is frequently abbreviated as character set, charset, or code set. For example, the capital letter "A" in the Latin alphabet might be represented by the code point 65. The concept of "coded character set" can also be thought of as a function that maps characters to code points. The repertoire may be closed, where no additions are allowed without creating a new standard, as it is the case with ASCII and most of the ISO-8859 series, or it may be open, allowing additions, as it is the case with Unicode.Ī collection of characters used to represent textual information, in which each character is assigned a numeric code point. Depending on the encoding scheme used, characters may be represented with different code units - sequence of bits used to represent a single character.Ī character repertoire is the full set of abstract characters a system supports. In Unicode, the character is the basic unit of encoding. It is also referred to as abstract character. In the context of an encoding convention, the term "character" refers to the abstract meaning, rather than a specific shape ( glyph), though in code tables some form of visual representation is also essential for the reader’s understanding. Common character encoding standards are US-ASCII, Extended ASCII, Unicode and UCS.Ī character is the smallest component of a written language that has semantic value. Depending of the character encoding convention used, the same text will end up with different binary representations. 6.1 Determining the Character Set for a FileĬharacter encoding is the process though which characters within a text document are represented by numeric codes and ultimately translate into sequence of bits stored on persistent storage or sent over the wire.5.8 Relationship between Unicode and UCS.5.7 Universal Character Set (UCS) ISO 10646.5.6.6 Unicode Transformation Format (UTF).
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