Nested Context Language: Difference between revisions

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{{Technical|date=September 2009}}

In the field of digital and interactive television, '''Nested Context Language''' (NCL) is a [[Declarative programming|declarative authoring language]] for [[hypermedia]] documents. NCL documents do not contain multimedia elements such as audio or video content; rather they function as a "glue" language that specifies how multimedia components are related. In particular, NCL documents specify how these components are synchronized relative to each other and how the components are composed together into a unified document. Among its main facilities, it treats hypermedia relations as first-class entities through the definition of hypermedia connectors, and it can specify arbitrary semantics for a hypermedia composition using the concept of composite templates.

'''Nested Context Language''' (NCL) is a declarative authoring language for [[hypermedia]] documents.

FollowingNCL othersis an [[XML]] standards,application NCLlanguage that is an extension of [[XHTML]], with XML elements and attributes specified by a modular approach. NCL modules can be added to standard web languages, such as [[XLink]] and [[Synchronized Multimedia Integration Language|SMIL]].

NCL is an [[XML]] application language, which provides several facilities for authoring a complete hypermedia document with synchronization relationships among its components. Among its main facilities, it treats hypermedia relations as first-class entities through the definition of hypermedia connectors, and it can specify arbitrary semantics for a hypermedia composition using the concept of composite templates.

NCL was initially designed for the Web environment, but a major application of NCL is use as the declarative language of the JapanesetheJapanese-Brazilian [[ISDB-Tb]] (International Standard for Digital Broadcasting) terrestrial DTV ([[digital TV)television]] [[middleware]] (named [[Ginga (SBTVD Middleware)|Ginga]]). It is also the first standardized technology of the [[ITU-T]] multimedia application framework series of specifications for [[IPTV]] (internet protocol television) services. In both cases it is used to develop interactive applications to digital television.

Following others XML standards, NCL is specified by a modular approach. NCL modules can be added to standard web languages, such as [[XLink]] and [[Synchronized Multimedia Integration Language|SMIL]].

NCL was initially designed for the Web environment, but a major application of NCL is use as the declarative language of the Japanese-Brazilian [[ISDB-Tb]] (International Standard for Digital Broadcasting) terrestrial DTV (digital TV) middleware (named [[Ginga (SBTVD Middleware)|Ginga]]). It is also the first standardized technology of the [[ITU-T]] multimedia application framework series of specifications for [[IPTV]] services. In both cases it is used to develop interactive applications to digital television.

==Structure of an NCL document==