Why did MPEG not build a new identification scheme for Digital Items?
Many content industries have developed and successfully deployed content identification scheme for their respective market segments. MPEGs DII specification leverages these existing identifier systems. But MPEG-21 DII does more: While MPEG-21 allows the compilation of Digital Items comprising resources from several content industries (e.g. a digital Item containing a sound recording and a text document), most of the existing identification schemes only allow the identification of content in one segment. MPEG-21s DII specification allows using the appropriate identifiers for different elements within Digital Items. For example the Digital Item above, comprising a sound recording and a text document, might contain identifiers for the sound recording (i.e. the ISRC) and the underlying musical work (i.e. the ISWC) and an identifier for the text document (i.e. an ISTC).
