...And once implemented, the implementation is more specific than the &quot;specification&quot; (a document detailing the requirements).<p>That&#x27;s why the OP said, correctly, that code is the highest level of specification, because nothing can be more specialized than code (as you said correctly, an implementation is less specialized than code).<p>Also cf. Operational Semantics (no, not denotational), which is literally the highest level of specification, and is runnable code.