code: function DeviceOnMap (map, data) {
      this.trace=[];  // keep trace of device trace on xx positions
      this.count=0;   // number of points created for this device
      this.devid = data.devid;
      this.src   = data.src;
      this.name  = data.name;
      this.cargo = data.cargo;
      this.vessel= ' cargo-' + data.cargo;
      this.map=map;
      this.lastshow = new Date().getTime();
  }
docs: Class to add vessel as POI on Leaflet