Video Subtitling



ASCII (American Standard Code for Information Interchange) is one of the early character encoding systems for computers. It is a 7 bit, 128 character system that was designed to represent the Latin alphabet, numerals and punctuation. It is not designed to represent characters from other alphabets. This often causes problems because many programming languages were originally developed for ASCII, and only later added support for Unicode and other character sets.


ATOM is a content syndication standard, similar to RSS, which allows websites to publish feeds that allow other sites, news readers and web servers to automatically read or import content from each other.

See also RSS.

bridge language

A bridge language is a widely spoken, international language, such as English, French or Spanish, that is used as an intermediate language when translating between two less widely spoken languages. For  example, to translate from Romanian to Chinese, one might translate first from Romanian to English, and then English to Chinese because few people speak Romanian and Chinese directly.

See also interlingua.

character Set

A character set can be as simple as a table that maps numbers to characters or symbols in an alphabet. ASCII, for example, is an old system that represents the American alphabet (the number 65 in ASCII equals 'a', for example).Unicode, in contrast, can represent a much larger range of symbols, including the large pictographic symbol sets for languages such as Chinese and Japanese.

character encoding

Character encoding is a representation of the sequence of numeric values for characters in text. For many character set standards, there is only one coding, so it is possible to confuse the two ideas. In Unicode, on the other hand, there is one numeric value for each character, but that value can be represented (encoded) in binary data of different lengths and formats. Unicode has 16-bit, 32-bit, and variable length encodings. The most important is UTF-8, which is to be used for all data transmission, including Web pages, because it is defined as a byte stream with no question of size or byte order. Fixed-length formats also have to specify processor byte order (Big-Endian or Little-Endian).

CMS (Content Management System)

A content management system is a piece of software that manages the process of editing and publishing content to a website or blog. A CMS enables editors to supervise the work of writers, manage how articles or posts are displayed, and so on. These systems also make it easier to separate content production (writing) from design related tasks, such as a page layout. Word Press, Movable Type, Drupal and Joomla are examples of widely used content management systems.


A corpus (plural corpora) is a large and structured collection of texts used for linguistic research. In the context of translation tools, a corpus consist of one or more aligned texts. These corpora typically contain texts that are about a certain domain and consequently can help to find the terminology used in a domain.


Copyleft is a use of copyright law to enforce policies that allow people to reprint, share and re-use published content without prior written permission from the author. Copyleft licences require that derivative works use the same licence, so that they are as Free as the original work.


Copyright is a form of intellectual property law giving the author of a work control over its use, re-use in different media, translation, and distribution.

Creative Commons

Creative Commons is an organization that was founded to promote new types of copyright terms, also known as copyleft. The organization has developed legal templates that define new policies for sharing and distributing online content without prior knowledge or consent from the original producer.


Disambiguation is the process of determining or declaring the meaning of a word or phrase that has several different meanings depending on its content. The English word "lie", for example, could mean "to recline" (I need to lie down), or "to tell a falsehood". Machine translation systems often have a very difficult time with this, while it is an easy task for humans, who can usually rely on context to determine which meaning is appropriate.

disambiguation markup

Disambiguation markup is a way to embed hints about the meaning of a word or phrase within a text, so that a machine translator or other automated process can understand what the author intended. For example, the expression "<div syn=similar>like</div>" would tell a text processor that the word like is synonymous with similar, information a program could use to avoid misinterpreting like as "to like someone".


The principal database and catalogue of human languages, providing linguistic and social data for each language. In particular, Ethnologue lists estimates of the number of speakers of each language in each country and worldwide. It is available in printed form and on the Internet at Ethnologue's database includes information on more than 6,900 known languages, and continues to grow.


Free, Libre and Open Source Software. An umbrella term for all forms of software which is liberally licensed to grant the right of users to study, change, and improve its design through the availability of its source code. FLOSS is an inclusive term generally synonymous with both free software and open source software which describe similar development models, but with differing cultures and philosophies.

fuzzy matching

Fuzzy matching is a technique used with translation memories that suggests translations that are not perfect matches for the source text.  The translator then has the option to accept the approximate match.  Fuzzy matching was meant to speed up translation however there is a greater risk of inaccuracy.


gettext is a utility, available in several programming languages, for localizing software. It works by replacing texts, or strings, with translations that are stored in a table, usually a file stored on a computer's disk drive. The table contains a list of x=y statements (e.g. "hello world" = "hola mundo").


GNU or GNU's Not Unix, is a recursive acronym for a set of software projects announced in 1983 by a computer scientist at MIT named Richard Stallman. The GNU project was designed to be a free, massively collaborative software, open source software initiative. In 1985 the Free Software Foundation was founded and took up the GNU project. It 1989 Stallman drafted a legal license for his software and called it the GPL or the GNU Public License. The GPL, a copyleft license, is the most popular license for free software.


An interlingua is a artificial language with extremely regular grammar that is used as an intermediate step when translating from one human language to another. This is an alternative to machine translation systems that translate the original text to an intermediate machine representation such as a parse tree, and then to the target human language.

The artificial language Interlingua is sometimes used as an interlingua in this sense. Several other artificial languages, including Esperanto, Loglan, and Lojban, have been proposed for the same purpose.

language code

A language code (see ISO) is a two or three letter code that uniquely identifies a human language. For example, en = English, while es = espanol / Spanish. There are two different code sets in widespread 
use. ISO 639-1 is a two letter code that represents several hundred languages, most of the widely spoken languages in use today, while ISO 639-2 and ISO 639-3 is a three letter code that represents a much larger set of languages (several thousand languages).

license / licensing

Licensing is the process of adding a legal license to your copyrighted work. This copyrighted work may be either a piece of content that can be translated or a software tool for translation. For more information on licensing, please see the chapter on it under Intellectual Property.

locale / locale code

A locale code, which is usually a suffix to a language code, provides additional geographical information. For example, Spanish varies by country, so you would identify Mexican Spanish as es-mx, while 
Argentine Spanish would have the code es-ar, where the suffix is the two letter ISO country code.


Localization is the process of translating and culturally adapting the prompts, instructions and user interface for a software application or web service. Most applications have dozens to hundreds of system menus and prompts that need to be translated.

machine translation

Machine translation is the computerised process of automatically generating a translation of text from one language to another.

machine translation (rules based)

A rules based translation engine tries to analyze a sentence, break it down into its parts of speech, and to interpret and disambiguate vocabulary to transform it into an intermediate, machine readable form. It then re-generates the intermediate form into the target language.

machine translation (statistical)

A statistical machine translation system works by sifting through extremely large sets of parallel or aligned texts (sentences that have been directly translated by humans from one language to another). With a sufficiently large training set, or corpora, it learns which phrases are strongly associated with counterparts in the other language. When translating texts, it works by breaking a text down into smaller fragments, called N-grams, and searches for the best statistical match into the target language, and generates a translation by stitching these translated texts together.


A microformat is an open data format standard for exchanging small pieces of information.

open content

Open Content, a neologism coined by analogy with "Open Source", describes any kind of creative work, or content, published under a licence that explicitly allows copying and modifying of its information by anyone, not exclusively by a closed organization, firm or individual. The largest Open Content project is Wikipedia.

Open Data Format Initiative

Initiative aiming to convince software companies to release data format documentation and to pass laws that governments can only store user in an open format.

open source software / licensing

To make software Open Source means to put it under a licence requiring that the human-readable source code be available freely on demand, with further rights to modify the program and redistribute the results. Source code under these licences is usually made available for download without restriction on the Internet.

Open Source software was originally defined as a derivative of the Debian Free Software guidelines, when Bruce Perens removed references to Debian from the definition. The current version of the definition is at

Open Source software is very similar to Free Software, but not at all like Freeware, which is provided at no cost, but without source code. Most Open Source software licences qualify as Free Software licences in the judgment of the Free Software Foundation. The term FLOSS is used to include both: Free (as in Libre) and Open Source Software.

open standards

An open standard is one created in a publicly accessible, peer reviewed, consensus-based process. Such standards should not depend on Intellectual Property unless it is suitably licensed to all users of the standard without fee and without application. Furthermore, open standards that define algorithmic processes should come with a GPLed or other Open Source reference implementation.

optical character recognition (OCR)

OCR is the conversion of images to text data, using various methods of shape recognition. The OCR software must recognize layout in addition to character glyphs, in order to represent word and paragraph spacing correctly in the resulting text, and if possible, columns and table layouts. Trainable OCR software can recognize text in a wide variety of fonts, and in some cases multiple writing systems. OCR for Chinese characters and for Arabic presents special problems, which have been to a considerable extent solved.

peer review

The process of reviewing a document by independent, possibly anonymous reviewers for quality defined by an appropriate professional standard and the requirements of a particular publication. Standards differ widely in different disciplines.

PO file

PO files (extension .po), are text files in a specified format, containing source and translated strings used by the gettext() localization system. Typically, you create one PO file for each language or locale that an application has been localized to.


Really Simple Syndication - a XML standard for syndicating information from a website,  commonly frequently updated databases such as news and events websites or blogs.

semantic network

A semantic network is a graph representation of words or phrases and their relationships to each other. In a semantic network, a word is linked to other words via paths, with descriptions of how they are linked. It can represent many types of relationships between words, such as: is similar to, is the opposite of, is a member of a set (e.g. "red" belongs to the set "colors").


A standard is defined by an authority or by general consent as a general rule or representation for a given entity.

standards body

A standards body is an organisation tasked with the definition and maintenance of standards, such as the IETF, which governs Internet standards, or the ITU (International Telecommunicaton Union), which sets standards for telephonic communication systems and networks.

SVG / Scalable Vector Graphics

SVG is a XML-based open format for resolution-independent vector graphic files, usually with extension .svg. This allows editing, and thus translation, of any <text> elements.

timebase / timebase code

A timebase code is used in video editing and subtitling to indicate where in a video a particular action, caption, etc takes place. The time is typically expressed as an offset from the beginning of the video clip, usually in a hh:mm:ss:ff form, where hh = hours, mm = minutes, ss=seconds and ff=frame number (e.g. 32 seconds, 12 frames into a clip display the caption "Hello World". There are a wide variety of ways this is done, but the basic concept is similar regardless of file format details.

translation memory

A translation memory is a database of source texts and their translations to one or more languages, as well as meta data about the translations, such as: who created the translation, subjective quality scores, revision histories, etc. The main characteristic of translation memories is that texts are segmented into translation units (blocks, paragraphs, sentences, or phrases) that are aligned with their corresponding translations. The standard for translation memory exchange between tools and/or translation vendors is TMX, an XML-based format developed by the Localization Industry Standards Association (LISA).


Transliteration is a systematic conversion of text from one writing system to another. It is not, in general, simple substitution of one letter for another. The purpose of a transliteration may be to represent the exact pronunciation of the original, or not; to indicate word structure and other linguistic attributes, or not; to represent text in a form familiar to the casual user, or not. There are more than 200 transliteration systems for representing Chinese in European alphabets, mostly Latin with some Cyrillic. Of these, only Pinyin is a standard recognized in China.

Changing fonts is not transliteration. There is, however, an unfortunate practice of creating so-called transliteration fonts, which substitute for the glyphs of a writing system glyphs from some other writing system. The practice is unfortunate because it produces bad transliterations even in the best of cases. Should the Korean family name 로 be transliterated Ro, as written, or No, as pronounced? Should the Spanish name Jimenez be transformed to Chimène in French, as happens sometimes to immigrants? It depends.


Unicode is the principal international character set, designed to solve the problem of large numbers of incompatible character sets using the same encoding. Unicode text can contain symbols from many languages, such as Arabic, English, and Japanese, along with Dingbats, math symbols, and so on. While not all languages are covered by Unicode, almost all official national languages are now part of the standard, except for traditional Mongolian script. In addition to encoding characters as numbers independent of any data representation, the Unicode standard defines character properties, Unicode Transformation Formats for representing Unicode text on computers, and algorithms for issues such as sorting (collation), and bidirectional rendering.


UTF-8 is a variable length Unicode Transformation Format that represents text as a stream of bytes. It was designed so that any ASCII text file (7 bits, with the 8th bit set to 0) is also a Unicode text file. This property does not extend to the 8-bit ISO 8859-1 or Windows Code Page 1252 character repertoires. Extended Latin characters require two bytes each, as do several other alphabets. Chinese characters and some other writing systems require three or four bytes per character. UTF-8 is specified as the appropriate form for transmitting Unicode text, regardless of the internal representation used on any particular computer.


A user editable website where users are authorized to create pages, and to create and edit content. Wikis range from open systems, where anyone can edit pages, to closed systems with controlled membership and access rights.

Word / Word Length

A computer word is a fixed-length sequence of bits, usually the same length as the registers in the processor. Thus 8-bit, 16-bit, and 32-bit words have been common in the history of computing, and other lengths have occasionally been used.

There is an unfortunate tendency to confuse computer word length with a variety of data types, including numbers and characters. This is most often seen in the mistaken notion that a character is a byte. Even during the period when all character set standards specified 7-bit or 8-bit representations, this was incorrect. Any byte could in fact represent dozens of characters, depending on its interpretation according to a particular character set definition. The idea became more wrong in the case of double-byte character sets for Chinese, Japanese, and Korean, where most characters had 16-bit representations. It is completely untenable in Unicode, where characters can be represented using 16-bit elements (including Surrogate pairs), 32-bit elements, or variable-length byte sequences, as in UTF-8.


XLIFF (XML Localization Interchange Format) is a standard format for storing localization data. It is widely used by translation memories and translation management tools as an interchange format.


eXtensible markup language is a system for expressing structured data within a text or html document. XML is similar in structure to HTML, and can be used as an interchange format for exchanging complex data structures between different computers. It is often described as a machine readable counterpart to HTML, which is designed to be read by humans. RSS, ATOM, SVG, and XLIFF are all XML based formats.