Awesome thanks! That's a great resource.
I'll put the code here for others to see an example.
Capabilities.json:
"displayUnits": { "displayName": "Display Units", "type": { "enumeration": [{ "value": "none", "displayName": "None" }, { "value": "thousands", "displayName": "Thousands" }, { "value": "millions", "displayName": "Millions" }, { "value": "billions", "displayName": "Billions" }] } }
And the enumeration is the same as you would get a string.