2.1.6 Future Record

The future record (section 2.1.6) architecture enables the file format to be extended with new or alternate content while maintaining compatibility with applications that do not support the new content. The future record architecture consists of a future record mechanism and an alternate content mechanism. The future record mechanism enables an application that does not support certain future records to open and save the file while ignoring but preserving those future records in the file, and correctly modifying cell references and formulas associated with the records. The alternate content mechanism enables an application to introduce extensions that target particular implementations.