their example shows

     "vehicleEngine": {
        "@type333": "EngineSpecification",
        "fuelType": "Gasoline333"
     },

where other, similar, examples do not have the "333" part. But its valid, apparently.

Do I even want to dive into the docs to find out what kind of hilarity this implies? Is this another one of the standards that are the products of sequential committees with no deadlines and generous recreational chemistry budgets?