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Nested Context Language
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<p>In the field of digital and interactive television, Nested Context Language (NCL) is a <a href="/facts/Declarative_programming/gogtdzcJ">declarative authoring language</a> for <a href="/facts/Hypermedia/90HarmoP">hypermedia</a> 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. </p><p>NCL is an <a href="/facts/XML/clNgUfWk">XML</a> application language that is an extension of <a href="/facts/XHTML/6qHnmJSg">XHTML</a>, with XML elements and attributes specified by a modular approach. NCL modules can be added to standard web languages, such as <a href="/facts/XLink/U1Mva8n2">XLink</a> and <a href="/facts/Synchronized_Multimedia_Integration_Language/JhWwHaa0">SMIL</a>. </p><p>NCL was initially designed for the Web environment, but a major application of NCL is use as the declarative language of the Japanese-Brazilian <a href="/facts/ISDB-Tb/6FDcvU0N">ISDB-Tb</a> (International Standard for Digital Broadcasting) terrestrial DTV <a href="/facts/Digital_television/KQCyILQa">digital television</a> <a href="/facts/Middleware/HobNosz9">middleware</a> (named <a href="/facts/Ginga_(SBTVD_Middleware)/ap1W7pzI">Ginga</a>). It is also the first standardized technology of the <a href="/facts/ITU-T/9nJwkPYx">ITU-T</a> multimedia application framework series of specifications for <a href="/facts/IPTV/tHqsXX6h">IPTV</a> (internet protocol television) services. In both cases it is used to develop interactive applications to digital television. </p>