While using the DB Access Module for ODBC, the database callbacks are invoked with respect to the allocation and deallocation of the RWDBODBCLibEnvironmentHandle and the SQLHENV it contains. The connection callbacks are invoked with respect to the allocation, deallocation, connect and disconnect of the RWDBODBCLibSystemHandle and the SQLHDBC it contains Please refer to the DB Interface Module User's Guide for more information.