Geomagnetic Model Web Service: General Help This web service makes the World Magnetic Model (WMM), the International Geomagnetic Reference Field (IGRF) and the BGS Global Geomagnetic Model (BGGM) available as a web service. The IGRF and WMM have no restrictions on use, the BGGM is only available to subscribers. The API provides options to select which model and revision to use. Values of the magnetic field at any point around the world can be retrieved for a given date. To see information about models view the 'models' help page (link = models) To see information about parameters view the 'parameters' help page (link = parameters)