A markup language is a modern system for annotating An annotation is a summary made of information in a book, document, online record, video, software code or other information, "in the margin", or perhaps just underlined or highlighted passages. Annotated bibliographies, give descriptions about how each source is useful to an author in constructing a paper or argument. Creating these a text in a way that is syntactically distinguishable from that text. The idea and terminology evolved from the "marking up" of manuscripts, i.e. the revision instructions by editors, traditionally written with a blue pencil on authors' manuscripts. Examples are typesetting instructions such as those found in troff troff is a document processing system developed by AT&T for the Unix operating system and LaTeX LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to create a document in LaTeX, a .tex file must be created, and structural markers such as XML XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards tags. Markup is typically omitted from the version of the text which is displayed for end-user consumption. Some markup languages, like HTML have presentation semantics In computer science, particularly in human-computer interaction, presentation semantics specify how a particular piece of a formal language is represented in a distinguished manner accessible to human senses, usually human vision. For example, saying that <bold> ... </bold> must render the text between these constructs using some bold, meaning their specification prescribes how the structured data is to be presented, but other markup languages, like XML, have no predefined semantics.

A well-known example of a markup language in widespread use today is HyperText Hypertext is text displayed on a computer or other electronic device with references to other text that the reader can immediately access, usually by a mouse click or keypress sequence. Apart from running text, hypertext may contain tables, images and other presentational devices. Hypertext is the underlying concept defining the structure of the Markup Language (HTML HTML, which stands for HyperText Markup Language, is the predominant markup language for web pages. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. It allows images and objects to be embedded and can be used to create interactive forms), one of the document formats of the World Wide Web The World Wide Web, abbreviated as WWW and commonly known as the Web, is a system of interlinked hypertext documents accessed via the Internet. With a web browser, one can view web pages that may contain text, images, videos, and other multimedia and navigate between them by using hyperlinks. Using concepts from earlier hypertext systems, British. HTML is mostly an instance of SGML The Standard Generalized Markup Language is an ISO-standard technology for defining generalized markup languages for documents. ISO 8879 Annex A.1 defines generalized markup: (though, strictly, it does not comply with all the rules of SGML) and follows many of the markup conventions used in the publishing industry in the communication of printed work between authors, editors, and printers.

Types

There are three general categories of electronic markup: Presentational, procedural, and descriptive.^[1][2]

Presentational markup is that used by traditional word-processing systems, binary codes embedded in document text that produced the WYSIWYG WYSIWYG , is an acronym for What You See Is What You Get. The term is used in computing to describe a system in which content displayed during editing appears very similar to the final output, which might be a printed document, web page, slide presentation or even the lighting for a theatrical event.[clarification needed] effect. Such markup is usually designed to be hidden from human users, even those who are authors or editors.

Procedural markup is embedded in text and provides instructions for programs that are to process the text. Well-known examples include troff troff is a document processing system developed by AT&T for the Unix operating system, LaTeX LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to create a document in LaTeX, a .tex file must be created, and PostScript PostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. PostScript is best known for its use as a page description language in the electronic and desktop publishing areas; it is expected that the processor runs through the text from beginning to end, following the instructions as encountered. Text with such markup is often edited with the markup visible and directly manipulated by the author. Popular procedural-markup systems usually include programming constructs, such that macros or subroutines can be defined and invoked by name. An example of descriptive markup would be the troff's .bd, which instructs the processor to switch to a bold-face font.

In Descriptive markup, the markup is used to label parts of the document rather than to provide specific instructions as to how they should be processed. The objective is to decouple the inherent structure of the document from any particular treatment or rendition of it. Such markup is often described as "semantic". An example of descriptive markup would be HTML's <cite> tag, which is used to label a citation.

There is considerable blurring of the lines between the types of markup. In modern word-processing systems, presentational markup is often saved in descriptive-markup-oriented systems such as XML XML is a set of rules for encoding documents in machine-readable form. It is defined in the XML 1.0 Specification produced by the W3C, and several other related specifications, all gratis open standards, and then processed procedurally by implementations. The programming constructs in descriptive-markup systems such as TeX TeX is a typesetting system designed and mostly written by Donald Knuth. Together with the METAFONT language for font description and the Computer Modern family of typefaces, it was designed with two main goals in mind: to allow anybody to produce high-quality books using a reasonable amount of effort, and to provide a system that would give the may be used to create higher-level markup systems which are more descriptive, such as LaTeX LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to create a document in LaTeX, a .tex file must be created.

In recent years, a number of small and largely unstandardized markup languages have been developed to allow authors to create formatted text via web browsers, for use in wikis Wikis may exist to serve a specific purpose, and in such cases, users use their editorial rights to remove material that is considered "off topic." Such is the case of the collaborative encyclopedia Wikipedia. In contrast, open purpose wikis accept content without firm rules as to how the content should be organized and web forums. The markup language used by Wikipedia Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 15 million articles have been written collaboratively by volunteers around the world, and almost all of its articles can be edited by anyone with access to the site. Wikipedia was launched in 2001 by Jimmy Wales is one such.

History

The term markup is derived from the traditional publishing practice of "marking up"' a manuscript A manuscript or handwrit is a recording of information that has been manually created by someone or some people, such as a hand-written letter, as opposed to being printed or reproduced some other way. The term may also be used for information that is hand-recorded in other ways than writing, for example inscriptions that are chiselled upon a hard, which involves adding handwritten annotations in the form of conventional symbolic printer Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing's instructions in the margins and text of a paper manuscript or printed proof Proofreading traditionally is the reading of a galley proof of text or art to detect and correct production errors. Computerization has required proofreaders to increasingly adopt skill-sets general to desktop publishing. For centuries, this task was done primarily by skilled typographers known as "markup men"^[3] or "copy markers"^[4] who marked up text to indicate what typeface In typography, a typeface is a set of one or more fonts, in one or more sizes, designed with stylistic unity, each comprising a coordinated set of glyphs. A typeface usually comprises an alphabet of letters, numerals, and punctuation marks; it may also include ideograms and symbols, or consist entirely of them, for example, mathematical or map-, style, and size should be applied to each part, and then passed the manuscript to others for typesetting Typesetting is the composition of text material by means of types by hand. Markup was also commonly applied by editors, proofreaders, publishers, and graphic designers, and indeed by document authors.

GenCode

The idea of using markup languages in computer text processing was probably first publicly presented by publishing executive William W. Tunnicliffe William W. Tunnicliffe is credited by Charles Goldfarb as being the first person (1967) to articulate the idea of separating the definition of formatting from the structure of content in electronic documents at a conference in 1967, although he preferred to call it "generic coding." It can be seen as a response to the emergence of programs such as RUNOFF that each used their own control notations, often specific to the target typesetting device. In the 1970s, Tunnicliffe led the development of a standard called GenCode for the publishing industry and later was the first chair of the International Organization for Standardization The International Organization for Standardization , widely known as ISO (pronounced /ˈaɪsoʊ/ EYE-soe), is an international-standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promulgates worldwide proprietary industrial and commercial standards. It has committee that created SGML The Standard Generalized Markup Language is an ISO-standard technology for defining generalized markup languages for documents. ISO 8879 Annex A.1 defines generalized markup:, the first standard descriptive markup language. Book designer Stanley Rice published speculation along similar lines in 1970.^[5] Brian Reid Brian Keith Reid is a computer scientist most famous for developing the Scribe word processing system, the subject of his 1980 doctoral dissertation, for which he received the Association for Computing Machinery's Grace Murray Hopper Award in 1982. Scribe was a pioneer in the use of descriptive markup. Reid presented a paper describing Scribe in, in his 1980 dissertation at Carnegie Mellon University Coordinates: 40°26′36″N 79°56′37″W / 40.443322°N 79.943583°W Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania. The university began as the Carnegie Technical Schools, founded by Andrew Carnegie in 1900. In 1912, the school became Carnegie Institute of Technology and began granting four-year, developed the theory and a working implementation of descriptive markup in actual use.

However, IBM International Business Machines (NYSE: IBM) is a multinational computer, technology and IT consulting corporation headquartered in Armonk, North Castle, New York, United States. IBM is the world's fourth largest technology company and the second most valuable by global brand (after Coca-Cola). IBM is one of the few information technology companies researcher Charles Goldfarb Charles F. Goldfarb is known as the father of SGML and is a co-inventor of the concept of markup languages. In 1969 Charles Goldfarb, leading a small team at IBM, developed the first markup language, called Generalized Markup Language, or GML. In an interview with Web Techniques Magazine editor Michael Floyd, Dr. Goldfarb explains that he coined is more commonly seen today as the "father" of markup languages. Goldfarb hit upon the basic idea while working on a primitive document management system intended for law firms in 1969, and helped invent IBM GML Generalized Markup Language is a set of macros that implement intent-based markup tags for the IBM text formatter, SCRIPT/VS. SCRIPT/VS is the main component of IBM's Document Composition Facility (DCF). A starter set of tags in GML is provided with the DCF product later that same year. GML was first publicly disclosed in 1973.

In 1975, Goldfarb moved from Cambridge, Massachusetts Cambridge is a city in Middlesex County, Massachusetts, United States, in the Greater Boston area. It was named in honor of the University of Cambridge in England, a nexus of the Puritan theology embraced by the town's founders. Notably, Cambridge is home to two internationally prominent universities, Harvard University and the Massachusetts to Silicon Valley Silicon Valley is the southern part of the San Francisco Bay Area in Northern California, United States. The term originally referred to the region's large number of silicon chip innovators and manufacturers, but eventually came to refer to all the high-tech businesses in the area; it is now generally used as a metonym for the American high-tech and became a product planner at the IBM Almaden Research Center The IBM Almaden Research Centre is in San Jose, California, and is one of IBM's eight worldwide research labs. Its scientists perform basic and applied research in computer science, services, storage systems, physical sciences, and materials science and technology. The centre opened in 1986, and continues the research started in San Jose more than. There, he convinced IBM's executives to deploy GML commercially in 1978 as part of IBM's Document Composition Facility product, and it was widely used in business within a few years.

Development informally began in 1978^{[citation needed]} on what ultimately became the SGML standard, which was based on both GML and GenCode; Goldfarb eventually became chair of the SGML committee. SGML was first and released by ISO as the ISO 8879 standard in October 1986.

Some early examples of computer markup languages available outside the publishing industry can be found in typesetting tools on Unix Unix is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna. Today's Unix systems are split into various branches, developed over time by AT&T as well as various commercial vendors and non-profit systems such as troff troff is a document processing system developed by AT&T for the Unix operating system and nroff nroff is a Unix text-formatting program; it produces output suitable for simple fixed-width printers and terminal windows. It is an integral part of the Unix help system, being used to format man pages for display. In these systems, formatting commands were inserted into the document text so that typesetting software could format the text according to the editor's specifications. It was a trial and error Trial and error, or trial by error or try an error, is a general method of problem solving, fixing things, or for obtaining knowledge. "Learning doesn't happen from failure itself but rather from analyzing the failure, making a change, and then trying again." iterative process to get a document printed correctly.^{[citation needed]} Availability of WYSIWYG WYSIWYG , is an acronym for What You See Is What You Get. The term is used in computing to describe a system in which content displayed during editing appears very similar to the final output, which might be a printed document, web page, slide presentation or even the lighting for a theatrical event.[clarification needed] ("what you see is what you get") publishing software supplanted much use of these languages among casual users, though serious publishing work still uses markup to specify the non-visual structure of texts, and WYSIWYG editors now usually save documents in a markup-language-based format.

TeX

Another major publishing standard is TeX TeX is a typesetting system designed and mostly written by Donald Knuth. Together with the METAFONT language for font description and the Computer Modern family of typefaces, it was designed with two main goals in mind: to allow anybody to produce high-quality books using a reasonable amount of effort, and to provide a system that would give the, created and continuously refined by Donald Knuth Donald Ervin Knuth (born January 10, 1938) is a renowned computer scientist and Professor Emeritus of the Art of Computer Programming at Stanford University in the 1970s and '80s. TeX TeX is a typesetting system designed and mostly written by Donald Knuth. Together with the METAFONT language for font description and the Computer Modern family of typefaces, it was designed with two main goals in mind: to allow anybody to produce high-quality books using a reasonable amount of effort, and to provide a system that would give the concentrated on detailed layout of text and font descriptions in order to typeset mathematical books in professional quality. This required Knuth to spend considerable time investigating the art of typesetting Typesetting is the composition of text material by means of types. However, TeX has a steep learning curve, so that it is mainly used in academia Academia, Acadème, or the Academy are collective terms for the community of students and scholars engaged in higher education and research, where it is the de facto standard in many scientific disciplines. A TeX macro package known as LaTeX LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to create a document in LaTeX, a .tex file must be created provides a descriptive markup system on top of TeX, and is widely used.

Scribe, GML and SGML

The first language to make a clear and clean distinction between structure and presentation was Scribe Scribe is a markup language and word processing system which pioneered the use of descriptive markup. Scribe was revolutionary when it was proposed, because it involved for the first time a clean separation of structure and format, developed by Brian Reid Brian Keith Reid is a computer scientist most famous for developing the Scribe word processing system, the subject of his 1980 doctoral dissertation, for which he received the Association for Computing Machinery's Grace Murray Hopper Award in 1982. Scribe was a pioneer in the use of descriptive markup. Reid presented a paper describing Scribe in and described in his doctoral thesis in 1980.^[6] Scribe was revolutionary in a number of ways, not least that it introduced the idea of styles separated from the marked up document, and of a grammar In linguistics, grammar is the set of structural rules that govern the composition of sentences, phrases, and words in any given natural language. The term refers also to the study of such rules, and this field includes morphology, syntax, and phonology, often complemented by phonetics, semantics, and pragmatics. Linguists do not normally use the controlling the usage of descriptive elements. Scribe influenced the development of Generalized Markup Language (later SGML) and is a direct ancestor to HTML and LaTeX.

In the early 1980s, the idea that markup should be focused on the structural aspects of a document and leave the visual presentation of that structure to the interpreter led to the creation of SGML. The language was developed by a committee chaired by Goldfarb. It incorporated ideas from many different sources, including Tunnicliffe's project, GenCode. Sharon Adler, Anders Berglund, and James A. Marke were also key members of the SGML committee.

SGML specified a syntax for including the markup in documents, as well as one for separately describing what tags were allowed, and where (the Document Type Definition (DTD) or schema). This allowed authors to create and use any markup they wished, selecting tags that made the most sense to them and were named in their own natural languages. Thus, SGML is properly a meta-language, and many particular markup languages are derived from it. From the late '80s on, most substantial new markup languages have been based on SGML system, including for example TEI and DocBook. SGML was promulgated as an International Standard by International Organization for Standardization, ISO 8879, in 1986.

SGML found wide acceptance and use in fields with very large-scale documentation requirements. However, it was generally found to be cumbersome and difficult to learn, a side effect of attempting to do too much and be too flexible. For example, SGML made end tags (or start-tags, or even both) optional in certain contexts, because it was thought that markup would be done manually by overworked support staff who would appreciate saving keystrokes^{[citation needed]}.

HTML

By 1991, it appeared to many that SGML would be limited to commercial and data-based applications while WYSIWYG tools (which stored documents in proprietary binary formats) would suffice for other document processing applications. The situation changed when Sir Tim Berners-Lee, learning of SGML from co-worker Anders Berglund and others at CERN, used SGML syntax to create HTML. HTML resembles other SGML-based tag languages, although it began as simpler than most and a formal DTD was not developed until later. Steven DeRose^[7] argues that HTML's use of descriptive markup (and SGML in particular) was a major factor in the success of the Web, because of the flexibility and extensibility that it enabled (other factors include the notion of URLs and the free distribution of browsers). HTML is quite likely the most used markup language in the world today.

Some^{[citation needed]} would restrict the term "markup language" to systems that directly support non-hierarchical structures (see Hierarchical model). By this definition HTML, XML, and even SGML (apart from its rarely-used CONCUR option) would be disqualified and called "container languages" instead. However, the term "container language" is not in widespread use, and such hierarchical languages are almost universally considered markup languages. There is active research on non-hierarchical markup models, some expressed within XML and related languages (for example, using the Text Encoding Initiative Guidelines and derivatives such as the Open Scripture Information Standard and CLIX), and some not (for example, MECS and the Layed Markup and Annotation Language or LMNL). Much of this research is published in the proceedings of the Extreme Markup and Balisage conferences, generally held in Montreal.

XML

XML (Extensible Markup Language) is a meta markup language that is now widely used. XML was developed by the World Wide Web Consortium, in a committee created and chaired by Jon Bosak. The main purpose of XML was to simplify SGML by focusing on a particular problem — documents on the Internet.^[8] XML remains a meta-language like SGML, allowing users to create any tags needed (hence "extensible") and then describing those tags and their permitted uses.

XML adoption was helped because every XML document can be written in such a way that it is also an SGML document, and existing SGML users and software could switch to XML fairly easily. However, XML eliminated many of the more complex and human-oriented features of SGML to simplify implementation environments such as documents and publications. However, it appeared to strike a happy medium between simplicity and flexibility, and was rapidly adopted for many other uses. XML is now widely used for communicating data between applications. Like HTML, it can be described as a 'container' language.

XHTML

Since January 2000 all W3C Recommendations for HTML have been based on XML rather than SGML, using the abbreviation XHTML (Extensible HyperText Markup Language). The language specification requires that XHTML Web documents must be well-formed XML documents – this allows for more rigorous and robust documents while using tags familiar from HTML.

One of the most noticeable differences between HTML and XHTML is the rule that all tags must be closed: empty HTML tags such as <br> must either be closed with a regular end-tag, or replaced by a special form: <br /> (the space before the '/' on the end tag is optional, but frequently used because it enables some pre-XML Web browsers, and SGML parsers, to accept the tag). Another is that all attribute values in tags must be quoted. Finally, all tag and attribute names must be lowercase in order to be valid; HTML, on the other hand, was case-insensitive.

Other XML-based applications

Many XML-based applications now exist, including Resource Description Framework (RDF), XForms, DocBook, SOAP and the Web Ontology Language (OWL). For a partial list of these see List of XML markup languages.

Features

A common feature of many markup languages is that they intermix the text of a document with markup instructions in the same data stream or file. This is not necessary; it is possible to isolate markup from text content, using pointers, offsets, IDs, or other methods to co-ordinate the two. Such "standoff markup" is typical for the internal representations that programs use to work with marked-up documents. However, embedded or "inline" markup is much more common elsewhere. Here, for example, is a small section of text marked up in HTML:

<h1> Anatidae </h1>
<p>
The family <i>Anatidae</i> includes ducks, geese, and swans,
but <em>not</em> the closely-related screamers.
</p>

The codes enclosed in angle-brackets <like this> are markup instructions (known as tags), while the text between these instructions is the actual text of the document. The codes h1, p, and em are examples of semantic markup, in that they describe the intended purpose or meaning of the text they include. Specifically, h1 means "this is a first-level heading", p means "this is a paragraph", and em means "this is an emphasized word or phrase". A program interpreting such structural markup may apply its own rules or styles for presenting the various pieces of text, using diffent typefaces, boldness, font size, indention, colour, or other styles, as desired. A tag such as "h1" (header level 1) might be presented in a large bold sans-serif typeface, for example, or in a monospaced (typewriter-style) document it might be underscored – or it might not change the presentation at all.

In contrast, the i tag in HTML is an example of presentational markup; it is generally used to specify a particular characteristic of the text (in this case, the use of an italic typeface) without specifying the reason for that appearance.

The Text Encoding Initiative (TEI) has published extensive guidelines for how to encode texts of interest in the humanities and social sciences, developed through years of international cooperative work. These guidelines are used by projects encoding historical documents, the works of particular scholars, periods, or genres, and so on.

Alternative usage

While the idea of markup language originated with text documents, there is an increasing usage of markup languages in other areas which involve the presentation of various types of information, including playlists, vector graphics, web services, content syndication, and user interfaces. Most of these are XML applications because it is a well-defined and extensible language.

The use of XML has also led to the possibility of combining multiple markup languages into a single profile, like XHTML+SMIL and XHTML+MathML+SVG^[9]

Because markup languages, and more generally data description languages (not necessarily textual markup), are not programming languages (they are data, not code), they are more easily manipulated than programming languages – for example, web pages are presented as HTML documents, not C code, and thus can be embedded within other web pages, displayed when only partially received, and so forth. This leads to the web design principle of the "Rule of Least Power", which advocates using the least (computationally) powerful that satisfies a task to facilitate such manipulation and reuse.

See also

• List of markup languages
• CSS (Cascading Style Sheets)
• Lightweight markup language
• User interface markup language
• Scalable Vector Graphics
• Vector graphics markup language
• ColdFusion Markup Language
• Parameter Value Language
• Curl (declarative markup and functional programming)
• Programming language (contrast)
• YAML (YAML is not a markup language, but it's close)
• Wikitext

Notes

• TEI guidelines
• Markup systems and the future of scholarly text processing by James H. Coombs, Allen H. Renear, and Steven J. DeRose. Originally published in the November 1987 CACM, and reprinted

References

1. ^ Coombs, James H.; Renear, Allen H.; DeRose, Steven J. (November 1987). "Markup systems and the future of scholarly text processing". Communications of the ACM (ACM) 30 (11): 933–947. http://cacm.acm.org/magazines/1987/11/10031-markup-systems-and-the-future-of-scholarly-text-processing/pdf.
2. ^ "Taxonomy of Markup". http://www.tbray.org/ongoing/When/200x/2003/04/09/SemanticMarkup#p-1.
3. ^ Allan Woods, Modern Newspaper Production (New York: Harper & Row, 1963), 85; Stewart Harral, Profitable Public Relations for Newspapers (Ann Arbor: J.W. Edwards, 1957), 76; and Chiarella v. United States, 445 U.S. 222 (1980).
4. ^ From the Notebooks of H.J.H & D.H.A on Composition, Kingsport Press Inc., undated (1960s).
5. ^ Rice, Stanley. “Editorial Text Structures (with some relations to information structures and format controls in computerized composition).” American National Standards Institute, March 17, 1970.
6. ^ Reid, Brian. "Scribe: A Document Specification Language and its Compiler." Ph.D. thesis, Carnegie-Mellon University, Pittsburgh PA. Also available as Technical Report CMU-CS-81-100.
7. ^ DeRose, Steven J. "The SGML FAQ Book." Boston: Kluwer Academic Publishers, 1997. ISBN 0-7923-9943-9
8. ^ http://www.w3.org/TR/2004/REC-xml11-20040204/ Extensible Markup Language (XML)
9. ^ An XHTML + MathML + SVG Profile". W3C, August 9, 2002. Retrieved on 17 March 2007.

External links

• World Wide Web Consortium (W3C)
• International Organization for Standardization (ISO)

Categories: Markup languages | Formal languages