V4F - I was waiting for that. I too am retired from FAA 6+ years and I was 1 of 2 that issued those at my facility and stiil have mine. And yes, they pass as a license most places outside the US like the old "pink card", however I was advised that their intended purpose was to give the FAA AOV branch (oversight) a tracking mechanism to be able to more easily look into who was having errors & deviations and were they being properly retrained, and should they be allowed to continue to work traffic. I have no idea what has happened with this program since 2008. I seems the FAA tried to move away from the facility alone determining what, if any, training was needed and if the controller should be given the opportunity to re-certified.
And the CREDENTIAL was issued to a US controllers after their FIRST position certification/validation. I believe most ICAO licenses are only issued after all positions are satisfied.
But yes, the CREDENTIAL will pass as a license if you have fully certified/validated and have a verifiable work history.