4National weather service noaa weather radio (NWR) transmitters NWR specific area messgae encoding, http://www.nws.noaa.gov/directives/.
5Emergency communications: the emergency alert system (eas) and all-hazard warnings.美国国会CRS报告.2004.
6ITU-T Recommendation X.1303. Common alerting protocol (CAP 1.1), 2007.
7Federal Information Processing Standard (FIPS) 6-4, counties and equivalent entities of the united states, its possessions, and associated areas, http://www.itl.nist .gov/fipspubs/fip6-4.htm.
