The primary reason for supporting parts of files are the radio/TV project: The project produces MPEG files of 12 and 24 hours length. A mechanism for extracting parts of these files are needed.
Given the robustness of the MPEG formats used, it should be possible to make efficient seeking and extraction. The maschine responsible for the file storage could provide access through http, thereby bystepping the need for the repository to make explicit support for splitting physical files. It would just be an external reference.