dev/defs/bones/bone.json

{
  "name": "Bone",
  "key": {
    "int": 40,
    "string": "bone"
  },
  "extends": "bones/skeletal_component.json",
  "properties": {
    "length": {
      "type": "double",
      "initialValue": "0",
      "animates": true,
      "key": {
        "int": 89,
        "string": "length"
      }
    }
  }
}