Jet engine
DAO were originally called VT Objects. DAO 1.0 came up in November 1992 as part of Access 1.0. In version 3.5 it was able to bypass the Jet engine altogether and directly access ODBC data sources, including Microsoft SQL Server and other enterprise database systems. DAO 3.6 shipped with Jet 4.0. Access 2007 and later uses ACE with its ACEDAO, where most new features supported by ACE are added to. ACEDAO no longer supports ODBCDirect.