Abstract: A method of retrieving a plurality of resource fragments from a audio-visual resource that is encoded using a hierarchical addressing model for the class of resources of which the audio-visual resource is a member is disclosed. The method comprises inputting a URI reference (1407) comprising a Universal Resource Identifier (1401) and a complex fragment identifier (1402) comprising a plurality of audio-visual resource specific location steps. Thereafter the method comprises a step of locating the audio-visual resource using the Universal Resource Name, and establishing (2023) a logical representation (2040) of the structure of the audio-visual resource. Then the method iteratively evaluates the fragment identifier location steps (1110) against the logical representation (2040) to resolve the complex fragment identifier (1402) into a set of explicit fragment references (1406) configured to explicitly address each of the plurality of resource fragments.