Defines: - How to uniquely identify Digital Items (and parts thereof); - How to uniquely identify IP related to the Digital Items (and parts thereof), for example abstractions; - How to express the relationship between the two above identifiers; - How to deal with varying levels of functional granularity for Digital Item identifiers; - How to uniquely identify Description Schemes; - The relationship between Digital Items (and parts thereof) and existing identification systems. Annex C contains a list of relevant identification systems.