A system for managing storage space on an electronic storage medium is provided in which a file format for stored data allows for progressive deletion of low-significance data, for example in a video or audio file, while allowing the remaining portions of the file to be subsequently retrieved. The file format allows for the ready deletion of low-significance data without having to open, edit and subsequently rewrite the data. Furthermore, rules-based algorithms for the deletion of low-significance data allow a user to store and progressively delete such low-significance data in accordance with time parameters, available storage space and the like, without having to delete the full file.