Topic summary
Forward-compatible
Extracted from the Wikipedia article Forward compatibility.
Relation to the robustness principle
Forward-compatible design is closely related to the robustness principle articulated by Jon Postel in RFC 761 (January 1980): "be conservative in what you do, be liberal in what you accept from others". The "liberal in what you accept" half of the principle describes the stance that a forward-compatible system takes toward unrecognized input; the "must ignore unknowns" rule can be read as a specific implementation of it.