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Glossary

• character  

  An atomic unit of content for text data. A character is an abstract entity without any particular appearance; characters include letters, digits, punctuation, and symbols.



• character encoding scheme  

  A text encoding that maps a sequence of characters (from one or more coded character sets) to a sequence of bytes, in order to combine characters from multiple coded character sets or to permit easier handling of some coded character sets. Compare coded character set.



• code fragment  

  See fragment.



• Code Fragment Manager (CFM)  

  In Mac OS 9 and earlier, refers to the part of the Macintosh system software that prepares fragments for execution.



• code point  

  An integer value that represents (or can represent) a character.



• coded character  

  A character together with its numeric representation in a particular coded character set.



• coded character set  

  A text encoding that maps each character in a set of characters to a particular integer from a set of integers. Compare character encoding scheme.



• code-switching scheme  

  A character encoding scheme that allows switching between different coded character sets, usually signaled by escape or other special sequences. See also character coding scheme.



• content transfer encoding  

  See transfer encoding syntax.



• converter object  

  An instance of data that tells a text converter how to convert text from a particular source encoding to a particular destination encoding, and maintains any necessary state information that applies to the conversion of a particular stream of text.



• destination encoding  

  The text encoding that describes the desired encoding of the text after conversion. Compare source encoding.



• direct conversion  

  A text conversion by the Text Encoding Converter that can be handled in one step (that is, by one call to a single plug-in). Compare indirect conversion.



• Extended UNIX Code (EUC)  

  A type of packing scheme that is used as the text encoding for UNIX workstations that handle East Asian languages. See also packing scheme.



• fallback mapping  

  A character or sequence of characters used to replace a character that has no direct equivalent in the destination encoding. For example, if the target encoding does not contain “å,” a possible fallback mapping would be “aa.”



• fragment  

  In Mac OS 9 and earlier, a fragment refers to a block of executable code or data. Fragments are handled by the Code Fragment Manager. See also Code Fragment Manager.



• glyph image  

  A visual element used to represent one or more characters.



• indirect conversion  

  A text conversion by the Text Encoding Converter that requires stepping through one or more intermediate conversions before reaching the desired destination encoding. Compare direct conversion.



• Internet  

  The name given to the world-wide network of computers.



• loose mapping  

  A mapping between text encodings that preserves the information content of text but does not permit round-trip fidelity.



• Multipurpose Internet Mail Extensions (MIME)  

  Mechanisms for specifying and describing the format of Internet message bodies.



• packing scheme  

  A type of character encoding scheme where characters are encoded using a variable number of bytes. Typically certain bytes signal the beginning of a character and how many additional bytes are used to encode the character. Character sets with a large number of elements are often stored using a packing scheme. See also character encoding scheme.



• perfect round-trip conversion  

  This occurs when mapping a character from a particular source encoding to a particular destination encoding (usually Unicode) and then back to the source encoding again yields the original character.



• plug in  

  See text encoding conversion plug-in.



• presentation form  

  An abstraction of a range of glyph images, which represents a standard way to display a particular character or group of characters in a particular context as specified by a particular writing system. See also glyph image.



• script  

  A collection of related characters, subsets of which are required to write a particular language. Some examples of scripts are Latin, Greek, Hiragana, Katakana, and Han.



• sniffer  

  A function included with a text conversion plug-in that scans text for features that identify a particular text encoding.



• source encoding  

  The text encoding that describes the encoding of the text before conversion. Compare destination encoding.



• strict mapping  

  A mapping between text encodings that preserves the information content of text and permits round-trip fidelity.



• text element  

  A group of one or more characters that is treated as a single entity for a particular process such as collation, display, or transcoding.



• text encoding  

  The coded character set or character encoding scheme used to represent a particular piece of text. See also coded character set, character encoding scheme.



• text encoding base  

  The primary specification of a text encoding, and one component of a text encoding specification. See also text encoding specification, text encoding variant, text encoding format.



• text encoding conversion plug-in  

  A code fragment that provides conversion services between pairs of encodings. A text encoding conversion plug-in informs the Text Encoding Conversion Manager about its conversion and encoding analysis capabilities



• text encoding format  

  A subset of the text encoding specification that specifies the byte format of the encoding. For example, a format might specify that the encoding take up only 7-bits for transmission over 7-bit channels. See also text encoding specification, universal transformation format.



• text encoding specification  

  A scalar value that defines a text encoding to be used in a conversion. It includes information about the text encoding base, the text encoding variant, and the text encoding format.



• text encoding variant  

  A specification of one among possibly several minor variants or subsets of a particular text encoding base. See also text encoding specification, text encoding base.



• Text Encoding Conversion Manager  

  A pair of shared library extensions—namely, the Text Encoding Converter and the Unicode Converter—that facilitate text encoding conversion on Mac OS–based computers



• Text Encoding Converter  

  A shared library extension that provides the services for general and algorithmic encoding conversions or multi-encoding streams. The Text Encoding Converter sometimes uses the Unicode Converter.



• transfer encoding syntax  

  A transformation applied to text encoded using a character encoding scheme to allow it to be transmitted by a specific protocol or set of protocols. This is normally used to permit 8-bit data to be sent through channels that can only handle 7-bit values. Also called content transfer encoding. Compare character encoding scheme, universal transformation format.



• Unicode  

  A universal character set that includes tens of thousands of characters covering the world’s major written languages along with many symbols.



• Unicode Converter  

  A shared library extension that provides table-based conversion between no-subset variants of Unicode, in either UTF-16 or UTF-8, and many other encodings.



• universal transformation format  

  Special formats that allow transmission of Unicode characters over 7-bit (UTF-7) and 8-bit (UTF-8) channels. See also transfer encoding syntax.



• writing system  

  A set of characters from one or more scripts that are used to write a particular language and the rules that govern the presentation of those characters.

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