Because of the extensibility and ability of integration of GML, we realize the integration and sharing of geo-data after we get the GML file of heterogeneous historical geo-data .

• 而一旦转换到GML这种能表达各种数据，并且可以在数据库间非常容易进行交换的格式后，才能说是从根本上实现了真正的地理数据的集成和共享。