informix and relational databases

My questions are: 1) Is informix a relational database server? 2) Can the relation between databases be built in the database or does it work at programing level? 3) How can I give a control database table field relations with other tables fields? Thanks.... :-) -- "And I'm happy, because you make me feel good, about me." - Melvin Udall ----------------------------------------------------------------- Mart'n Marqu's email: martin@math.unl.edu.ar Santa Fe - Argentina http://math.unl.edu.ar/~martin/ Administrador de sistemas en math.unl.edu.ar -----------------------------------------------------------------