server 4dClient Expansion The number of Client Expansion licenses determine the number of devices that can connect at the same time to the 4D Server. These licenses are to be installed on the 4D Server. Purchase additional Client Expansions toThe 4D Server is mandatory for any 4D solution deployment. It integrates a powerful relational database, ORDA (Object Relational Data Access), that is an enhanced technology to use this database as an object, an SQL server, a