{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "CityJSON Extension specifications v0.9",
  "type": "object",

  "definitions": {

    "Plus": {
      "patternProperties": {
        "(\\+)\\w+": {}
      },
      "additionalProperties": false
    }

  },


  "properties": {
    "type": { "enum": ["CityJSON_Extension"] },
    "name": { 
      "type": "string",
      "pattern": "^\\w[a-zA-Z@#0-9.]*$",
      "description": "no spaces allowed"
    },
    "version": { 
      "type": "string",
      "pattern": "^(\\d\\.)(\\d+\\.)?(\\*|\\d+)$"
    },
    "uri": { 
      "type": "string",
      "format": "uri-reference",
      "description": "good to host the extension at a URI so that others can access it"
    },
    "description": { "type": "string" },
    "definitions": {},
    
    "extraRootProperties":{
      "patternProperties": {
        "(\\+)\\w+": {}
      },
      "additionalProperties": false
    },

    "extraAttributes": {
      "type": "object",
      "properties": {
        "CityObjectGroup": { "$ref": "#/definitions/Plus" },
        "Building": { "$ref": "#/definitions/Plus" },
        "BuildingPart": { "$ref": "#/definitions/Plus" },
        "BuildingInstallation": { "$ref": "#/definitions/Plus" },
        "Road": { "$ref": "#/definitions/Plus" },
        "Railway": { "$ref": "#/definitions/Plus" },
        "TransportSquare": { "$ref": "#/definitions/Plus" },
        "TINRelief": { "$ref": "#/definitions/Plus" },
        "WaterBody": { "$ref": "#/definitions/Plus" },
        "LandUse": { "$ref": "#/definitions/Plus" },
        "GenericCityObject": { "$ref": "#/definitions/Plus" },
        "CityFurniture": { "$ref": "#/definitions/Plus" },
        "SolitaryVegetationObject": { "$ref": "#/definitions/Plus" },
        "PlantCover": { "$ref": "#/definitions/Plus" },
        "Bridge": { "$ref": "#/definitions/Plus" },
        "BridgePart": { "$ref": "#/definitions/Plus" },
        "BridgeInstallation": { "$ref": "#/definitions/Plus" },
        "BridgeConstructionElement": { "$ref": "#/definitions/Plus" },
        "Tunnel": { "$ref": "#/definitions/Plus" },
        "TunnelPart": { "$ref": "#/definitions/Plus" },
        "TunnelInstallation": { "$ref": "#/definitions/Plus" }
      },
      "additionalProperties": false
    },

    "extraCityObjects": {
      "patternProperties": {
        "(\\+)([A-Z])\\w+": {}
      },
      "additionalProperties": false
    }

  },
  "required": ["type", "name", "version", "uri"],
  "additionalProperties": false
}