In order to address the needs of modern researchers to share and access research outcomes, Digital Library Systems (DLSs) evolved to manage new types of documents and collections which surpass the traditional publication-metadata document model to incorporate further entities involved in the research life-cycle. For example, enhanced publications enrich the representation of traditional publications with other objects, such as metadata descriptions, research datasets, cited publications, etc. To cope with such representational requirements, modern Digital Library Management Systems (tools supporting DLS construction, ref. DELOS Digital Library Manifesto) tend to offer data models capable of expressing DLS document models as “labeled graphs of information objects”. As a consequence, DLSs evolved also in the way they export their objects to third-party applications. Typically, objects are organized into “packages of interlinked information objects”, known as compound objects.
