In Unicode, a script is a collection of letters and other written signs used to represent textual information in one or more writing systems.[1] Some scripts support one and only one writing system and language, for example, Armenian. Other scripts support many different writing systems; for example, the Latin script supports English, French, German, Italian, Vietnamese, Latin itself, and several other languages. Some languages make use of multiple alternate writing systems and thus also use several scripts; for example, in Turkish, the Arabic script was used before the 20th century but transitioned to Latin in the early part of the 20th century. More or less complementary to scripts are symbols and Unicode control characters.
The unified diacritical characters and unified punctuation characters frequently have the "common" or "inherited" script property. However, the individual scripts often have their own punctuation and diacritics, so that many scripts include not only letters but also diacritic and other marks, punctuation, numerals and even their own idiosyncratic symbols and space characters.
Unicode 16.0 defines 168 separate scripts, including 99 modern scripts and 69 ancient or historic scripts.[2][3] More scripts are in the process for encoding or have been tentatively allocated for encoding in roadmaps.[4]
Definition and classification
When multiple languages make use of the same script, there are frequently some differences, particularly in diacritics and other marks. For example, Swedish and English both use the Latin script. However, Swedish includes the character å (sometimes called a Swedish O), while English has no such character. Nor does English make use of the diacritic combining ring above for any character. In general, the languages sharing the same scripts share many of the same characters. Despite these peripheral differences in the Swedish and English writing systems, they are said to use the same Latin script. Thus, the Unicode abstraction of scripts is a basic organizing technique. The differences among different alphabets or writing systems remain and are supported through Unicode’s flexible scripts, combining marks and collation algorithms.
Script versus writing system
Writing system is sometimes treated as a synonym for "script". However, it also can be used as the specific concrete writing system supported by a script. For example, the Vietnamese writing system is supported by the Latin script. A writing system may also cover more than one script; for example, the Japanese writing system makes use of the Han, Hiragana and Katakana scripts.
Most writing systems can be broadly divided into several categories: logographic, syllabic, alphabetic (or segmental), abugida, abjad and featural; however, all features of any of these may be found in any given writing system in varying proportions, often making it difficult to purely categorize a system. The term complex system is sometimes used to describe those where the admixture makes classification problematic.
Unicode supports all of these types of writing systems through its numerous scripts. Unicode also adds further properties to characters to help differentiate the various characters and the ways they behave within Unicode text-processing algorithms.
Special script property values
In addition to explicit or specific script properties, Unicode uses three special values:[5]
Common
Unicode can assign a character in the UCS to a single script only. However, many characters—those that are not part of a formal natural-language writing system or are unified across many writing systems—may be used in more than one script (for example, currency signs, symbols, numerals and punctuation marks). In these cases Unicode defines them as belonging to the "common" script (ISO 15924 code "Zyyy").
Inherited
Many diacritics and non-spacing combining characters may be applied to characters from more than one script. In these cases Unicode assigns them to the "inherited" script (ISO 15924 code Zinh), which means that they have the same script class as the base character with which they combine, and so in different contexts they may be treated as belonging to different scripts. For example, U+0308̈COMBINING DIAERESIS may combine either with U+0065eLATIN SMALL LETTER E to create a Latin ë or with U+0435еCYRILLIC SMALL LETTER IE for the Cyrillicё. In the former case, it inherits the Latin script of the base character, whereas in the latter case, it inherits the Cyrillic script of the base character.
Unknown
The value of "unknown" script (ISO 15924 code Zzzz) is given to unassigned, private-use, noncharacter, and surrogate code points.
Character categories within scripts
Unicode provides a general category property for each character. So in addition to belonging to a script every character also has a general category. Typically scripts include letter characters including: uppercase letters, lowercase letter and modifier letters. Some characters are considered titlecase letters for a few precomposed ligatures such as Dz (U+01F2). Such titlecase ligatures are all in the Latin and Greek scripts and are all compatibility characters, and therefore Unicode discourages their use by authors. It is unlikely that new titlecase letters will be added in the future.
Most writing systems do not differentiate between uppercase and lowercase letters. For those scripts all letters are categorized as "other letter" or "modifier letter". Ideographs such as Unihan ideographs are also categorized as "other letters". A few scripts do differentiate between uppercase and lowercase however: Latin, Cyrillic, Greek, Armenian, Georgian, and Deseret. Even for these scripts there are some letters that are neither uppercase nor lowercase.
Scripts can also contain any other general category character such as marks (diacritic and otherwise), numbers (numerals), punctuation, separators (word separators such as spaces), symbols and non-graphical format characters. These are included in a particular script when they are unique to that script. Other such characters are generally unified and included in the punctuation or diacritic blocks. However, the bulk of characters in any script (other than the common and inherited scripts) are letters.
List of encoded scripts
As of version 16.0[update], Unicode defines 168 scripts (called "Alias" or "Property value alias") based on the ISO 15924 list. In addition, Unicode assigns the name "Common" to ISO 15924's Zyyy code for undetermined scripts, "Inherited" to ISO 15924's Zinh code for inherited scripts, and "Unknown" to ISO 15924's Zzzz code for uncoded scripts. There are script codes defined by ISO 15924 but are not used in Unicode, including Zsym (Symbols) and Zmth (Mathematical notation).
Unicode uses the "Property Value Alias" (Alias) as the script-name. These Alias names are part of Unicode and are published informatively next to ISO 15924. An alias script name may be used in a character name: Palm, Palmyrene →U+10860𐡠PALMYRENE LETTER ALEPH.
With each new version of Unicode, new writing systems are added to the international character code. According to a statement by linguist Dr Deborah Anderson of UC Berkeley, there are over 100 writing systems that have not yet been included in Unicode.
According to a list of the project Missing Scripts by the University of Applied Sciences Mainz, Germany, the ANRT Nancy, France and UC Berkeley, USA, there are 294 known writing systems of mankind according to the current state of research (January 2022). 131 of them have not yet been encoded in Unicode, i.e. cannot yet be used on a computer or mobile phone.
Unicode, formally The Unicode Standard, is a text encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 of the standard defines 154998 characters and 168 scripts used in various ordinary, literary, academic, and technical contexts.
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Letter case is the distinction between the letters that are in larger uppercase or capitals and smaller lowercase in the written representation of certain languages. The writing systems that distinguish between the upper- and lowercase have two parallel sets of letters: each in the majuscule set has a counterpart in the minuscule set. Some counterpart letters have the same shape, and differ only in size, but for others the shapes are different. The two case variants are alternative representations of the same letter: they have the same name and pronunciation and are typically treated identically when sorting in alphabetical order.
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BC. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as well as consonants. In Archaic and early Classical times, the Greek alphabet existed in many local variants, but, by the end of the 4th century BC, the Euclidean alphabet, with 24 letters, ordered from alpha to omega, had become standard and it is this version that is still used for Greek writing today.
ISO 15924, Codes for the representation of names of scripts, is an international standard defining codes for writing systems or scripts. Each script is given both a four-letter code and a numeric code.
Unicode has subscripted and superscripted versions of a number of characters including a full set of Arabic numerals. These characters allow any polynomial, chemical and certain other equations to be represented in plain text without using any form of markup like HTML or TeX.
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Unicode supports several phonetic scripts and notation systems through its existing scripts and the addition of extra blocks with phonetic characters. These phonetic characters are derived from an existing script, usually Latin, Greek or Cyrillic. Apart from the International Phonetic Alphabet (IPA), extensions to the IPA and obsolete and nonstandard IPA symbols, these blocks also contain characters from the Uralic Phonetic Alphabet and the Americanist Phonetic Alphabet.
The Latin script, also known as the Roman script, is a writing system based on the letters of the classical Latin alphabet, derived from a form of the Greek alphabet which was in use in the ancient Greek city of Cumae in Magna Graecia. The Greek alphabet was altered by the Etruscans, and subsequently their alphabet was altered by the Ancient Romans. Several Latin-script alphabets exist, which differ in graphemes, collation and phonetic values from the classical Latin alphabet.
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