The growth of multi-level modeling has resulted in an increase of level-organization alternatives which significantly differ from each other with respect to their underlying foundations and the well-formedness rules they enforce. Alternatives substantially diverge with respect to how level boundaries should govern instance-of relationships, what modeling mechanisms they employ, and what modeling principles they establish. In this article I analyze how a number of multi-level modeling approaches deal with certain advanced modeling scenarios. In particular, I identify linear domain metamodeling, i.e., the requirement that all domain-induced instance-of relationships align with a single global level-hierarchy, as a source of accidental complexity. I propose a novel multi-dimensional multi-level modeling approach based on the notion of orthogonal ontological classification that supports modeling of domain scenarios with minimal complexity while supporting separation of concerns and sanity-checking to avoid inconsistent modeling choices.

Thomas is an Associate Professor at Victoria University of Wellington. His research interests focus on multi-level modeling and model-driven development. He is an editor for the Springer journal Software and Systems Modeling from which he received a ten year most influential regular paper award. He also received two ACM SIGSOFT distinguished paper awards. He received his PhD from Darmstadt University of Technology. Thomas was the general chair for MODELS 2011, organised the inaugural SoSyM Theme Issue on Multi-Level Modeling, and co-organised the Dagstuhl Seminar 17492 “Multi-Level Modelling”. Thomas is the MODELS 2023 Practice Track Chair.