Mindtagger: Defining categorical tags/labels

[v-makh]

I'm struggling with the right tag schema to define a simple categorical tag (e.g. object_type can take 1 of N possible values).

Ideally, for the tag, I'd like the possible values to be listed as a drop down menu or an array of buttons and the user can select one. I'm not sure what the right way is for defining the tag schema for this task. I'm using the following but it just returns an "N/A" labeled button.

{                        
    "object type": {     
        "type": "parametric",  
        "params": "string",    
        "values": [ "A", "B", "C" ]                                                       
    }                                                                                
}  

Any help appreciated!