The ability to accept input from lATer versions of itself. Forward compATibility is harder to achieve than {backward compATibility}, since, in the backward case, the input formAT is know whereas a forward compATible system needs to cope gracefully with unknown future feATures. An example of future compATibility is the stipulATion thAT a web browser should ignore HTML tags it does not recognise. See also extensible. (2003-06-23)