Research of self-adaptive systems can benefit from different exemplars to test and compare research methods and results. Although the number of exemplars for this area is rising, the exemplars for decentralized self-adaptive systems are limited. To that end, we introduce dTAS (decentralized Tele-Assistance System), an exemplar in the domain of service-based systems that targets decentralized adaptation of entities equipped with a classic MAPE-K feedback loop. dTAS offers predefined features that enable users to specify systems and plug in MAPE components with protocols to coordinate adaptation using different coordination patterns. We illustrate the exemplar for a scenario with three entities where the planner components coordinate the adaptation to realize their adaptation goals. © 2020 IEEE.