Custom Visual - format property of "scripting" type?

Hi all - can anyone point me to any documentation or example of using the "scripting" value type within the format properties of a custom visual? I'm having difficulty in finding anything that will tell me what it's for or how to use it.

In the capabilities schema, it's defined as

"scripting": {		
     "type": "object",		
     "description": "A text value that will be displayed to the user as a script",		
     "properties": {		
          "source": {		
              "type": "boolean",		
              "description": "A source code"		
          }		
     }		
}

I've been able to define a property successfully in my visual (it compiles), ie

        "scriptTest": {
            "displayName": "Script Test",
            "properties": {
                "something": {
                    "type": { 
                        "scripting": {
                            "source": true
                        } 
                    }
                }
            }
        }

but I don't know how to use it in the enumerateObjectInstances method. Any help greatly appreciated