{
    items: [
        {   label:  "checkin 1",
            type:   "checkin",
            file:   [ "file 1", "file 2" ]
        },
        {   label:  "checkin 2",
            type:   "checkin",
            file:   [ "file 3", "file 4" ]
        },
        {   label:  "file 1",
            type:   "file",
            add:    10,
            remove: 2
        },
        {   label:  "file 2",
            type:   "file",
            add:    10,
            remove: 5
        },
        {   label:  "file 3",
            type:   "file",
            add:    5,
            remove: 7
        },
        {   label:  "file 4",
            type:   "file",
            add:    5,
            remove: 2
        }
    ],
    properties: {
        "file" : {
            valueType: "item"
        }
    }
}