json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "id": "https://github.com/route4me/json-schemas/blob/master/TrackingHistory.dtd",
      "title": "Tracking History",
      "type": "object",
      "required": [
          "s",
          "lt",
          "lg",
          "ts",
          "ts_friendly"
      ],
      "properties": {
          "s": {
              "type": [
                  "number",
                  "null"
              ],
              "title": "Speed",
              "description": "Speed at the time of the location transaction event"
          },
          "lt": {
              "type": [
                  "number",
                  "null"
              ],
              "title": "Latitude",
              "description": "Latitude at the time of the location transaction event"
          },
          "lg": {
              "type": [
                  "number",
                  "null"
              ],
              "title": "Longitude",
              "description": "Longitude at the time of the location transaction event"
          },
          "d": {
              "type": [
                  "string",
                  "null"
              ],
              "title": "Direction",
              "description": "Direction/Heading at the time of the location transaction event"
          },
          "ts": {
              "type": [
                  "string",
                  "null"
              ],
              "title": "Timestamp",
              "description": "The original timestamp in unix timestamp format at the moment location transaction event"
          },
          "ts_friendly": {
              "type": [
                  "string",
                  "null"
              ],
              "title": "Friendly Timestamp",
              "description": "The original timestamp in a human readable timestamp format at the moment location transaction event"
          }
      }
  }