This standard defines a conceptual model for interpreting externalized representations of digital aggregations of resources for learning@ education@ and training. The conceptual model defines a set of concepts and the relationships among them and is expressed as a formal ontology. Internal compositions and uses of digital resources are not specified nor are processing methods for resource aggregations. Purpose Currently@ resource aggregations used in learning@ education@ and training are defined in a variety of standards and specifications. The conceptual model defined in this standard facilitates interoperability by providing an ontology that can be used to represent a variety of aggregation formats. Interoperability may be achieved by the creation of crosswalks among the various aggregation standards and specifications. In addition@ this standard may serve as a common reference for the development and evolution of standards and specifications for resource aggregations and may assist the development of profiles that maximize interoperability between the various aggregation formats.