Most Ingres data types have a corresponding C language data type. Data values passed between the application and a server use the C language data formats. For data types that do not have corresponding C language data types—namely money, decimal, and date—OpenAPI provides two functions, IIapi_convertData() and IIapi_formatData(), which convert these values to a native C language format. The introduction of new data types is controlled by an OpenAPI level negotiated by the IIapi_connect() function.