This Recommendation specifies the nested context language (NCL) and an NCL presentation engine called Ginga-NCL to provide interoperability and harmonization among IPTV multimedia application frameworks. To provide global standard IPTV services, it is foreseeable that a combination of different standard multimedia application frameworks will be used. Therefore, this Recommendation specifies the nested context language, as one of those standard multimedia application frameworks, to provide interoperable use of IPTV services. Ginga-NCL is an NCL presentation engine that integrates NCL and Lua players into a declarative environment. NCL and Lua frameworks can be used in other declarative environments, but if they are used together they shall follow Ginga-NCL specification.