Markup language
A markup language is a text-encoding system which specifies the structure and formatting of a document and potentially the relationship between its parts.[1] Markup can control the display of a document or enrich its content to facilitate automated processing.
A markup language is a set of rules governing what markup information may be included in a document and how it is combined with the content of the document in a way to facilitate use by humans and computer programs. The idea and terminology evolved from the "marking up" of paper manuscripts (e.g., with revision instructions by editors), traditionally written with a red pen or blue pencil on authors' manuscripts.[2]
Older markup languages, which typically focus on typography and presentation, include Troff, TeX, and LaTeX.
Scribe and most modern markup languages, such as XML, identify document components (for example headings, paragraphs, and tables), with the expectation that technology, such as stylesheets, will be used to apply formatting or other processing.
Some markup languages, such as the widely used HTML, have pre-defined presentation semantics, meaning that their specifications prescribe some aspects of how to present the structured data on particular media. HTML, like DocBook, Open eBook, JATS, and many others, is based on the markup meta-languages SGML and XML. That is, SGML and XML allow designers to specify particular schemas, which determine which elements, attributes, and other features are permitted, and where.
A key characteristic of most markup languages is that they allow intermingling markup with document content such as text and pictures. For example, if a few words in a sentence need to be emphasized, or identified as a proper name, defined term, or another special item, the markup may be inserted between the characters of the sentence.
Etymology[edit]
The noun markup is derived from the traditional publishing practice called "marking up" a manuscript,[3] which involves adding handwritten annotations in the form of conventional symbolic printer's instructions — in the margins and the text of a paper or a printed manuscript.
For centuries, this task was done primarily by skilled typographers known as "markup men"[4] or "markers"[5] who marked up text to indicate what typeface, style, and size should be applied to each part, and then passed the manuscript to others for typesetting by hand or machine.
The markup was also commonly applied by editors, proofreaders, publishers, and graphic designers, and indeed by document authors, all of whom might also mark other things, such as corrections, changes, etc.
History of markup languages[edit]
GenCode[edit]
The first well-known public presentation of markup languages in computer text processing was made by William W. Tunnicliffe 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 chairman of the International Organization for Standardization committee that created SGML, the first standard descriptive markup language. Book designer Stanley Rice published speculation along similar lines in 1970.[9]
Brian Reid, in his 1980 dissertation at Carnegie Mellon University, developed the theory and a working implementation of descriptive markup in actual use. However, IBM researcher Charles Goldfarb 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 later that same year. GML was first publicly disclosed in 1973.
In 1975, Goldfarb moved from Cambridge, Massachusetts to Silicon Valley and became a product planner at the IBM Almaden Research Center. 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.
SGML, which was based on both GML and GenCode, was an ISO project worked on by Goldfarb beginning in 1974.[10] Goldfarb eventually became chair of the SGML committee. SGML was first released by ISO as the ISO 8879 standard in October 1986.
Language[edit]
While the idea of markup language originated with text documents, there is increasing use of markup languages in the presentation of other types of information, including playlists, vector graphics, web services, content syndication, and user interfaces. Most of these are XML applications because XML 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.[25]