 The word ‘implementation’ is often associated with a physical realization of a computing system, i.e., to a machine executing a computer program. In particular, according to the dual ontology of computing systems examined in  §1.1,  implementation in this sense reduces to the structural hardware, as opposed to the functional software. By contrast, following the method of the levels of abstraction  (§ 1.2),  implementation becomes a wider relation holding between any LoA defining a computational system and the levels higher in the hierarchy. Accordingly, an algorithm is an implementation of a (set of) specification(s); a program expressed in a high level programming language can be defined as an implementation of an algorithm (see  §4);  assembly and machine code instructions can be seen as an implementation of a set of high-level programming language instructions with respect to a given ISA; finally, executions are physical, observable, implementations of those machine code instructions. By the same token, programs formulated in a high-level language are also implementations of specifications, and, as similarly argued by the dual-ontology paradigm, executions are implementations of high-level programming language instructions. According to Turner (2018), even the specification can be understood as an implementation of what has been called intention.