"Physical" is potentially not the right term as then I think of atoms and physical matter and encoding bits using magnetic fields or other physical means as electric currents or punch cards.

I would rather use Machine Perspective as can be conveyed by the fact that the low-level encoding that can directly be understood by the machine is, for instance, the "binary code", which is also often referred to as "machine code".

Even then what you imply is probably a level higher as you state: "specifically, with how the canonical representation of expression logic is shared between producers and consumers". The latter makes me thing of something like: "Realization" or "Communication" Perspective.

Existing Wording:

3.3. Physical Perspective

Proposed Wording:

3.3 Realization Perspective