IFF files are extensible and forward/backward compatible: o Chunk contents should be designed for compatibility across environments and for longevity. Every chunk should have a path for future expansion; at minimum this will be an unused bit or two. o The standards team for a FORM type can extend one of the chunks that contains a structure by appending new, optional structure fields. o Anyone can define new FORM types as well as new chunk types within a FORM type. Storing private chunks within a FORM is OK, but be sure to register your activities with Commodore Applications and Technical Support. o A chunk can be superseded by a new chunk type, e.g., to store more bits per RGB color register. New programs can output the old chunk (for backward compatibility) along with the new chunk. o If you must change data in an incompatible way, change the chunk ID or the FORM type ID.