This is Part (a) of Deliverable D1.4, which specifies the final CHOReOS conceptual model, that is, a high level common ground capturing the relevant concepts and the relationships, underlying the CHOReOS development process and the supporting infrastructures of choreography-based serviceoriented systems of the Future Internet. The conceptual model has been defined by means of an iterative process that started with the representation of preliminarily identified concepts, which were the focus of Deliverable D1.2 [15]. Then, the model has been incrementally extended/refined by using the MOTHIA tool that reduced the knowledge gap between the domain and modeling experts while iterating the refinement process. The CHOReOS conceptual model extends NEXOF-RA by introducing new concepts and refining existing ones. It is organized into nine concerns that will be individually described in the document: Composition, Discovery, Analysis, Messaging, Services, Resource, Management, Presentation, and Security.