 The fact that correctness criteria for the implementation relation are provided by the abstract level induces Turner (2012, 2014, 2018) to define implementation as the relation specification-artefact. As examined in  §2,  specifications have correctness jurisdiction over artifacts, that is, they prescribe the allowed behaviors of artifacts. Also recall that artifacts can be both abstract and concrete entities, and that any LoA can play the role of specification for lower levels. This amounts to saying that the specification-artefact relation is able to define any implementation relation across the layered ontology of computational systems.