MPEG-21 DIDL defines a conceptual d

MPEG-21 DIDL defines a conceptual data model and its representation as an XML bytestream. The container, item, component, resource, and descriptor objects are represented as nested XML elements. Therefore, an ID/IDREF linking mechanism for linking different sections is, unlike in METS, not necessary. Unlike METS, DIDL provides few attributes for capturing technical or descriptive metadata. Figure 5 illustrates the MPEG-21 DIDL architecture.
.