The Lookup web service contains methods that provide access to data that is primarily used for field validation or to populate GUI elements (e.g., state dropdown list).
Sample Code: lookups.aspx
GetLocationsForCity
Returns the locations that are valid for the given Country, State and City combination. There will be one County element returned for each related County and one ZipCode element for each related Zip Code.
GetLocationsForCountry
Returns the States, Counties, Cities and Zip Codes that are valid for the given Country. There will be one Location element returned for each related Location (State, County, City and Zip Code combination).
GetLocationsForCounty
Returns the locations that are valid for the given Country, State and County combination. There will be one City element returned for each related City and one ZipCode element for each related Zip Code.
GetLocationsForState
Returns the locations that are valid for the given Country and State combination. There will be one County element returned for each related County, one City element returned for each related City, and one ZipCode element for each related Zip Code.
GetLocationsForZipCode
Returns the locations that are valid for the given Country and Zip Code combination. There will be one State element returned for each related State, one County element returned for each related County, one City element returned for each related City, and one ZipCode element for each related Zip Code.
Additional information, including each methods response XML structure, is provided in the documentation and more example code is provided in the Gateway Sample application.