Online Appendix for Evolution Support for Custom Variability Artifacts using Feature Models: A Study in the Cyber-Physical Production Systems Domain

Cyber-Physical Production Systems (CPPSs) are highly configurable production systems with real-time control and self-adaptive behaviour. CPPSs are often tailored to customer needs or environmental requirements, which creates a highly variable, multidisciplinary environment. A sound documentation of their variability is required to foster component reuse. For this purpose, the Software Product Line (SPL) community proposed many different variability modeling approaches, which are used to explicitly model common and variable characteristics of a set of (software-intensive) systems. Unfortunately, industry is mostly unaware of the plethora of existing variability modeling approaches from academia and frequently develops their own custom solutions, e.g., spreadsheet-based representations or Domain-Specific Languages (DSLs). This document is the online appendix of the paper Evolution Support for Custom Variability Artifacts using Feature Models: A Study in the Cyber-Physical Production Systems Domain. The paper investigates the product line evolution impact on PPR--DSL artifacts compared to feature models. The aim is to better understand the system evolution impact differences and work towards enabling industrial practitioners to evolve their custom variability artifacts supported by a variability model. Therefore, the paper uses two case study systems, i.e., the Water filter and the Rocker switch cases, from the CPPS domain