Note that elements and typese are all external (can be referenced in importing and including documents. Container to describe a multi-source mashup. A package of multiple sources. This is the root element of the XML file. A small amount of DC metadata to describe the mashup The URI at which the source item is located Each source must contain a location URI and some metadata in extensible formats. REQUIRED: The location URI of a source document. The URI must conform to RFC 2396 (http://www.ietf.org/rfc/rfc2396.txt).