## 2 Related Work  
Despite numerous contributions and discussions in the field of M2M transformations, visual model-based M2M transformations remain very relevant to date. For an extensive evaluation of the existing M2M transformation approaches and their engineering solutions, we refer the reader to a recent survey by [PERSON] et al. [21], which examines over 60 available tools for M2M transformation development, including many well-known CASE tools, and evaluates their technical, modeling, and other relevant capabilities, including aspects related to the user experience. They also provide a classification of the analyzed tools, grouping them into declarative, imperative, graph-based, and hybrid approaches. Further, the main focus is on the most relevant visual modeling-based tools. A significant number of existing solutions are based on triple graph grammar formalism [22], including eMoflon [1], EMorf [2], and Henshin [23]. The original paper on eMoflon presents its implementation as an extension for the Enterprise Architect CASE tool and discusses the application of UML profiles. In this respect, it is similar to the basic principles of our approach, in particular regarding its modularity, extensibility, and reusability. EMorf, based on the eclipse modeling framework (EMF), is used for the development of model-based M2M transformations and supports visual modeling using visual editor, palette, and different views. It also provides support for the interactive application of transformation rules on selected concepts or all possible matches; this bears certain similarities to our approach, which also offers an agile approach to selecting individual transformations involving subsets of model concepts. [PERSON]'s [23] approach is also similar to our approach in its way of visually presenting M2M transformations as transformation rules with left-hand side (LHS) and right-hand side (RHS) elements; also, UML metamodel concepts are used for specification of transformation models. The aforementioned EMF [24] also followed a similar principle by utilizing ECore metaclasses to specify transformation rules with certain structural constraints. When compared to our approach, the main difference lies in the general use and modularity of the developed transformations. These tools are applied for full-scale M2M transformations; meanwhile, our approach supports agile, selective application of partial M2M transformations throughout multiple projects and application domains. [PERSON] et al. [25] described an imperative transformation modeling technique based on story-driven modeling (SDM), which leverages UML profiling technology. This technique was later applied to develop the MoTMoT transformation approach, which combines SDM imperative modeling with declarative modeling of TGG rules; the MagicDraw tool was used as a platform to implement this approach [26]. It was proven to be applicable for both M2M modeling and model refactoring tasks [27]. This research showed that the modern CASE tool with UML profiling support can be successfully transformed into a powerful transformation modeling environment, which is also one of the key features of our approach. Moreover, features of conciseness, readability, maintainability, efficiency, and scalability were also addressed [27], which reconfirmed our experimental findings in [14]. Next to model-driven development of M2M transformations, constraint specification is another significant feature in the area of M2M transformations. As shown in this paper, conditional processing is mandatory to enable advanced transformation scenarios. Some available solutions rely on OMG's Object Constraint Language (OCL), which is a dedicated language for the specification of constraints in UML diagrams. It was used in some solutions that relied on UML class diagrams [28; 29; 30]. Several more recent works also consider OCL as a base language to formalize or embed constraints in their transformation tools [2; 31].