Many testbeds owning devices or applications interacting with the sensors, store their inherent observations and other related data in their own proprietary format. In other words, making a testbed independent and isolated from others that cannot directly interact with each other. Differences in the data format lead to interoperability issues between the testbeds and much work has to be done in order to ensure the compatibility. One has to understand different data formats and create the mapping between them. As a result, a testbed must understand other testbed's format and create the mapping both while sending and receiving information. One method to accomplish interoperability is through the usage of semantic-based technologies to annotate all the information shared by the platforms. Nevertheless, some of the relevant existing ontologies promise interoperability but: - do not address the problem to describe the observation in an interoperable manner to ease further tasks, such as reasoning, - many of them are domain-specific and cannot be applied across domains, - they have missing concepts and do not suffice the needs of the measurements provided by the sensors, and - many ontologies do not follow best practices making it hard to correctly interpret and reuse concepts. In order to address the above-mentioned limitations, we provide FIESTA-IoT ontology (a unified semantic model) that follows best practices. FIESTA-IoT Ontology is a merge of concepts from various ontologies such as IoT-lite, M3-lite Taxonomy, SSN, Time and DUL. For more details please see: - R. Agarwal, D. Fernandez, T. Elsaleh, A. Gyrard, J. Lanza, L. Sanchez, N. Georgantas, V. Issarny, "Unified IoT Ontology to Enable Interoperability and Federation of Testbeds", 3rd IEEE WF-IoT, Reston, VA, USA, 12-14 December 2016. (https://hal.inria.fr/hal-01386917/document).