DSpace identifies two levels of digital preservation: bit preservation, and functional preservation. Bit preservation ensures that a file remains exactly the same over time – not a single bit is changed – while the physical media evolve around it. Functio

DSpace identifies two levels of digital preservation: bit preservation, and functional preservation. Bit preservation ensures that a file remains exactly the same over time – not a single bit is changed – while the physical media evolve around it. Functional preservation goes further: the file does change over time so that the material continues to be immediately usable in the same way it was originally while the digital formats (and the physical media) evolve over time. Some file formats can be functionally preserved using straightforward format migration (e.g. TIFF images or XML documents). Other formats are proprietary, or for other reasons are much harder to preserve functionally