Last week in Dad’s response to the OGP/OP post, he dropped another abbreviation, COA.
Certificate of Authenticity. This is a piece of paper from a mint that authenticates that the coin is real. It may include the number of the coin and other details.
This Certificate of Authenticity is a little tri-fold that indicates this coin is number 0433 and was struck by the Perth Mint for the Coin Club of Australia in 2012. The middle back gives technical specifications.
Also, please note this bullion coin has all the OGP!