What is "forward compatibility"

n. (context software English) Capability of interoperate with anticipated future systems.

Forward compatibility is a design characteristic that allows a system to gracefully accept input intended for a later version of itself. The concept can be applied to entire systems, electrical interfaces, telecommunication signals, data communication protocols, file formats, and computer programming languages. A standard supports forward compatibility if a product that complies with earlier versions can " gracefully" process input designed for later versions of the standard; the ability of a system to select known input and ignore unknown input also depends on whether the new standard is backward compatible.

The objective for forward compatible technology is for old devices to recognise when data has been generated for new devices.

Forward compatibility is not the same as extensibility. A forward compatible design can process at least some of the data from a future version of itself. An extensible design makes upgrading easy. An example of both design ideas can be found in web browsers. At any point in time, a current browser is forward compatible if it gracefully accepts a newer version of HTML. Whereas how easily the browser code can be upgraded to process the newer HTML determines how extensible it is.

The degree to which forward compatibility is harder than backward compatibility depends entirely on how much of the future system is unknown.