Presented before ISO/IEC JTC1/SC7/WG42, Meeting #42, on 11 November 2024, in support of the architecture/design distinction in ISO/IEC/IEEE 42024, Architecture fundamentals.

The talk sets out the Locality Criterion: a statement is local if and only if it is preserved under expansion. Architectural statements are exactly the non-local ones — those a program can violate by growing. Worked examples separate architectural statements from detailed design, and the criterion is applied to Garlan, Allen and Ockerbloom’s Architectural Mismatch (1995) to make non-local assumptions explicit.

Based on A. H. Eden and R. Kazman, “Architecture, Design, Implementation”, ICSE 2003, pp. 149–159, and A. H. Eden, R. Kazman, and Y. Hirshfeld, “Abstraction Classes in Software Design“, IEE Software, Vol. 153, No. 4, pp. 163–182. London, UK: The Institution of Engineering and Technology