"expr":"# obtain geographical location as a \"geohash\" label\r\nlabel_join(device_attribute{host=\"$station\", device=\"stat/antennafield/$antennafield\", name=\"Antenna_Reference_GEOHASH_R\"}, \"geohash\", \"\", \"str_value\")\r\n\r\n# obtain antenna name as an \"antenna_name\" label\r\n* on(idx) group_right(geohash)\r\nlabel_join(device_attribute{host=\"$station\", device=\"stat/antennafield/$antennafield\", name=\"Antenna_Names_R\"}, \"antenna_name\", \"\", \"str_value\")\r\n\r\n# obtain the value of the marker\r\n* on(idx) group_right(geohash, antenna_name)\r\ndevice_attribute{host=\"$station\", device=\"stat/antennafield/$antennafield\", name=\"ANT_mask_RW\"} != bool 0",