In pc textual content processing, a markup language is a system for annotating a doc in a approach that’s syntactically distinguishable from the textual content, that means when the doc is processed for show, the markup language just isn’t proven, and is barely used to format the textual content. The concept and terminology advanced from the “marking up” of paper manuscripts (i.e., the revision directions by editors), which is historically written with a crimson pen or blue pencil on authors’ manuscripts. Such “markup” sometimes contains each content material corrections (comparable to spelling, punctuation, or motion of content material), and likewise typographic directions, comparable to to make a heading bigger or boldface.
The first well-known public presentation of markup languages in pc textual content processing was made by William W. Tunnicliffe at a convention in 1967, though he most well-liked to name it generic coding. It might be seen as a response to the emergence of packages comparable to RUNOFF that every used their very own management notations, typically particular to the goal typesetting gadget. In the Nineteen Seventies, Tunnicliffe led the event of an ordinary referred to as GenCode for the publishing business and later was the primary chairman of the International Organization for Standardization committee that created SGML, the primary commonplace descriptive markup language. Book designer Stanley Rice printed hypothesis alongside related traces in 1970.
In the current years, quite a lot of small and largely unstandardized markup languages have been developed to permit authors to create formatted textual content by way of net browsers, comparable to those utilized in wikis and in net boards. These are typically referred to as light-weight markup languages. Markdown, BBCode, and the markup language utilized by Wikipedia are examples of such languages.
There is appreciable blurring of the traces between the varieties of markup. In trendy word-processing methods, presentational markup is commonly saved in descriptive-markup-oriented methods comparable to XML, after which processed procedurally by implementations. The programming in procedural-markup methods, comparable to TeX, could also be used to create higher-level markup methods which can be extra descriptive in nature, comparable to LaTeX.
There are three predominant normal classes of digital markup, articulated in Coombs, et al. (1987), and Bray (2003).
The noun markup is derived from the normal publishing observe referred to as “marking up” a manuscript, which entails including handwritten annotations within the type of typical symbolic printer’s directions — within the margins and the textual content of a paper or a printed manuscript. It is jargon utilized in coding proof. For centuries, this process was accomplished primarily by expert typographers referred to as “markup males” or “d markers” who marked up textual content to point what typeface, type, and measurement must be utilized to every half, after which handed the manuscript to others for typesetting by hand or machine. Markup was additionally generally utilized by editors, proofreaders, publishers, and graphic designers, and certainly by doc authors, all of whom may also mark different issues, comparable to corrections, adjustments, and so forth.
One extraordinarily necessary attribute of most markup languages is that they permit mixing markup instantly into textual content streams. This occurs on a regular basis in paperwork: A couple of phrases in a sentence have to be emphasised, or recognized as a correct title, outlined time period, or different particular merchandise. This is kind of completely different structurally from conventional databases, the place it’s by definition inconceivable to have information that’s (for instance) inside a file, however not inside any area. Likewise, markup for pure language texts should keep ordering: it will not suffice to make every paragraph of a e book right into a “paragraph” file, the place these data don’t keep order.
Some markup languages, such because the broadly used HTML, have pre-defined presentation semantics—that means that their specification prescribes some points of the best way to current the structured information on explicit media. HTML, like DocBook, Open eBook, JATS and numerous others, is a particular software of the markup meta-languages SGML and XML. That is, SGML and XML allow customers to specify explicit schemas, which decide simply what parts, attributes, and different options are permitted, and the place.
Early markup methods sometimes included typesetting directions, as troff, TeX and LaTeX do, whereas Scribe and most trendy markup methods title parts, and later course of these names to use formatting or different processing, as within the case of XML.
In digital media, this “blue pencil instruction textual content” was changed by tags which ideally point out what the elements of the doc are, somewhat than particulars of how they is perhaps proven on some show. This lets authors keep away from formatting each occasion of the identical type of factor redundantly (and presumably inconsistently). It additionally avoids the specification of fonts and dimensions which can not apply to many customers (comparable to these with different-size shows, impaired imaginative and prescient and screen-reading software program).