NotationalDesign is a methodology by which program design, and especially user interface design, is seen as an instance of ProgrammingLanguageDesign. It is closely related to the InterpreterPattern (and to a lesser extent the CommandPattern), but goes further by merging both the ScriptingLanguage and the DomainSpecificLanguage into a single whole. 

While not usually known by this name, NotationalDesign is widely used in LispLanguage and SmalltalkLanguage programming. The premiere example NotationalDesign is the EmacsEditor. 
- JayOsako
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see ApplicationsAreLanguages