Fixed-Meaning Canon.
Words must be given the meaning they had when the text was adopted.Antonin Scalia and Bryan A. Garner
That is, at the time the Commonwealth of Australia Constitution was enacted, “Commonwealth” and “Commonwealth entity” or “Parliament of the Commonwealth” meant the non-corporate Commonwealth of the People under a Monarch, and a “Commonwealth” entity/Government/agent was one pursuant to our Constitution, not the Corporations Act 2001 or other Acts that regulate corporations.
and,
Public Governance, Performance and Accountability Act 2013
https://www.legislation.gov.au/Details/C2017C00269
11 Types of Commonwealth entities
There are 2 types of Commonwealth entities:
(a) a corporate Commonwealth entity, which is a Commonwealth entity that is a body corporate; and
(b) a non‑corporate Commonwealth entity, which is a Commonwealth entity that is not a body corporate.
Note: Corporate Commonwealth entities are legally separate from the Commonwealth, whereas non‑corporate Commonwealth entities are part of the Commonwealth.